Which one of the following is most strongly supported by the information above?

This is a Most Strongly Supported question.

Lathyrism, a debilitating neurological disorder caused by the consumption of the legume lathyrus sativus, is widespread among the domestic animals of some countries.

We’re told two facts about lathyrism in this sentence: (1) it’s widespread among the domestic animals of some countries, and (2) it’s a debilitating neurological disorder caused by eating a certain kind of plant.

Attempts to use rats to study lathyrism have generally failed.

We’ve tried to study this disorder in rats – but these attempts have mostly failed. Interesting – why have they failed? Are we going to start using some other animal in our studies? And can that animal be my neighbor’s Pomeranian?

Rats that ingested Lathyrus sativus did not produce the symptoms associated with the disorder.

This does provide an explanation of why using rats to study lathyrism hasn’t been useful – the rats that ate the plant that causes lathyrism don’t have the symptoms of lathyrism. Since we don’t see the symptoms in these rats, it’s tough to learn anything about lathyrism from them. For the sake of science, we need our test subjects to suffer the debilitating effects of this neurological disorder!

The stimulus doesn’t seem structured to lead to a particular conclusion. Let’s go to the answers and look for something that’s most strongly supported.

Answer Choice (A) The physiology of rats is radically different from that of domestic animals.

This may be a tempting answer, since it is a potential explanation for why rats don’t seem to experience the symptoms of lathyrism. But the problem is it’s far too speculative. We have no reason to think that this explanation is more likely than any other potential explanation.

Another issue is that even if we could say that some physiological difference in rats is why they don’t experience symptoms of lathyrism, that does not support the claim that rat physiology is radically different from domestic animals. “Radically different” means extremely different. But maybe there’s only a small difference that accounts for the rat’s resistance to the symptoms; we have no reason to think that there must be some extreme difference in physiology. Even a small difference in one’s bodily functions might lead to widely varying resistance to diseases.

Answer Choice (B) The rats did not consume as much Lathyrus sativus as did the domestic animals that contracted lathyrism.

This is similar to (A) in that it’s also offering a potential explanation of why rats did not exhibit symptoms. But we just don’t know how much the rats ate. It’s possible that they ate less than the domestic animals, and that this is why the rats didn’t experience the symptoms. But we don’t know – nothing in the stimulus speaks to the amount of the plants the rats ate.

Correct Answer Choice (C) Not all animal species are equally susceptible to lathyrism.

This is supported, because we know that rats don’t produce the symptoms of lathyrism, whereas at least some other animals do. The stimulus doesn’t explicitly say that other animals experience the symptoms, but the first sentence states that lathyrism is a “debilitating neurological disorder,” which means that it must have some effect on at least some animal in the world. If it didn’t, then it wouldn’t make sense to call the disorder debilitating. Since rats are affected differently from lathyrism compared to at least some other animals, that means lathyrism has varying effects on at least some animals in the world.

Sometimes people have a problem with the word “susceptible” in this answer. But susceptible means “liable to be influenced or harmed by a particular thing.” If rats don’t produce symptoms of lathyrism, but some other animal does, it’s fair to say that rats are less susceptible to lathyrism than the other animal. Rats are not as liable to be influenced or harmed by lathyrism.

Answer Choice (D) Most of the animals that can contract lathyrism are domestic.

“Most” means over half. The stimulus doesn’t support the claim that over half of animals that can get lathyrism are domestic. Although we know that lathyrism is “widespread among the domestic animals of some countries,” that doesn’t speak to what proportion of animals that can get lathyrism are domestic. For example, maybe lathyrism affects many cows, pigs, chickens, and hopefully, my neighbor’s Pomeranian. But it could be that lathyrism also affects lions, tigers, deer, wolves, monkeys, and every single wild animal in the world. The number of wild animals affected could be a lot greater than the number of domestic animals affected.

Answer Choice (E) Laboratory conditions are not conducive to the development of lathyrism.

Like (A) and (B), (E) is also an attempt to explain why the rats were asymptomatic. But we don’t know whether lab conditions are the reason that the rats mentioned in the stimulus didn’t produce symptoms of lathyrism. This explanation is possible but far too speculative since the stimulus doesn’t say anything that makes this explanation for the rats’ resistance to lathyrism any more likely than some other explanation (such as rats having some genetic resistance or other natural defense against lathyrism).


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Lathyrism, a debilitating neurological disorder caused by the consumption of the legume Lathyrus sativus, is widespread among the domestic animals of some countries. Attempts to use rats to study lathyrism have generally failed. Rats that ingested Lathyrus sativus did not produce the symptoms associated with the disorder.

Summary
The stimulus says that eating Lathyrus sativus (L.S.) can cause domestic animals to develop a severe disorder called lathyrism. However, researchers have failed to use rats to study lathyrism. This is because rats that ate L.S. didn’t develop lathyrism symptoms.

Strongly Supported Conclusions
These conclusions are strongly supported:
Not all animals that eat L.S. will develop lathyrism.
Rats are less vulnerable to lathyrism than at least some other animals.

A
The physiology of rats is radically different from that of domestic animals.
This is not supported. The stimulus doesn’t offer any general facts about the physiology of rats versus domestic animals. We don’t even know why rats don’t develop lathyrism, let alone if it’s due to a “radical” difference in physiology.
B
The rats did not consume as much Lathyrus sativus as did the domestic animals that contracted lathyrism.
This is not supported. Nothing in the facts suggests how much L.S. is needed to cause lathyrism in domestic animals, how much the affected domestic animals actually eat, nor how much was given to the rats.
C
Not all animal species are equally susceptible to lathyrism.
This is strongly supported. The stimulus says that rats don’t develop lathyrism from eating L.S., even though lathyrism is widespread in some domestic animal species. This lets us infer that different species of animals have different susceptibility to lathyrism.
D
Most of the animals that can contract lathyrism are domestic.
This is not supported. The stimulus mentions that lathyrism occurs in some domestic animals, but doesn’t indicate whether or not it can occur in non-domestic animals. Because we don’t know anything about non-domestic animals, we can’t compare.
E
Laboratory conditions are not conducive to the development of lathyrism.
This is not supported. The facts strongly imply that the problem with these lathyrism studies is that rats don’t develop lathyrism; nothing suggests that the laboratory conditions themselves are to blame. We don’t even know for sure if the studies happen in a laboratory!

74 comments

Marmosets are the only primates other than humans known to display a preference for using one hand rather than the other. Significantly more marmosets are left-handed than are right-handed. Since infant marmosets engage in much imitative behavior, researchers hypothesize that it is by imitation that infant marmosets learn which hand to use, so that offspring reared by left-handed parents generally share their parents’ handedness.

Summarize Argument: Phenomenon-Hypothesis
The researchers hypothesize that most marmosets become left-handed because they imitate their parents as babies. Why? Because infant marmosets are known to imitate frequently.

Notable Assumptions
The researchers assume there’s no alternative or additional explanation accounting for the prevalence of left-handedness among marmosets. In particular, they assume baby marmosets tend to imitate their parents, and that genetic factors don’t determine a marmoset’s handedness.

A
A study conducted on adult marmosets revealed that many were right-handed.
This doesn’t affect the researchers’ argument. It’s stated only that “[s]ignificantly more” marmosets are left-handed than right-handed, which is compatible with the existence of many right-handed marmosets, provided there are also lots of left-handed marmosets out there.
B
Right-handed marmosets virtually all have at least one sibling who is left-handed.
This weakens the researchers’ argument. It implies left-handed and right-handed marmosets are frequently raised by the same parents, making it less likely that marmosets tend to acquire the same handedness as their parents.
C
According to the study, 33 percent of marmosets are ambidextrous, showing equal facility using either their left hand or their right hand.
This doesn’t affect the researchers’ argument. It doesn’t change the relative prevalence of left-handed marmosets, nor does it imply the researchers are basing their hypothesis on faulty evidence.
D
Ninety percent of humans are right-handed, but those who are left-handed are likely to have at least one left-handed parent.
This implies humans tend to acquire their handedness from their parents, not that humans—or marmosets—acquire their handedness through imitation. There are many reasons, besides their tendency to imitate, why marmosets might, unlike humans, tend to be left-handed.
E
Marmosets raised in captivity with right-handed adult marmosets to whom they are not related are more likely to be right-handed than left-handed.
This supports the researchers’ hypothesis that handedness is developed through imitation, rather than solely genetic or environmental factors. It implies baby marmosets tend to acquire their handedness from other, nearby marmosets—not just from genetic relatives.

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