A
Most of the species of birds that were attracted by the trees that were planted did not eat mosquitoes.
B
The species of birds that were attracted in the greatest number by the fruit of the trees that were planted did not eat mosquitoes.
C
The birds attracted to the area by the trees ate many more insects that prey on mosquitoes than they did mosquitoes.
D
Since the trees were planted, the annual precipitation has been below average, and drier weather tends to keep mosquito populations down.
E
Increases and decreases in mosquito populations tend to follow a cyclical pattern.
Jake: Companies have recently introduced antibacterial household cleaning products that kill common bacteria on surfaces like countertops and floors. It’s clear that people who want to minimize the amount of bacteria in their homes should use cleaning products that contain antibacterial agents.
Karolinka: But studies also suggest that the use of these antibacterial cleaning products can be harmful, since common bacteria that survive the use of these products will eventually produce strains of bacteria that are resistant to antibiotics. That’s why antibacterial agents should not be used in household cleaning products.
Speaker 1 Summary
Jake claims that people who want to reduce bacteria in their homes should use antibacterial cleaning products. Why? Because these products kill common bacteria on household surfaces.
Speaker 2 Summary
Karolinka argues that cleaning products shouldn’t use antibacterial agents. As support, Karolinka says that studies show that antibacterial cleaning products can be harmful. How so? Because their use can produce antibiotic-resistant bacteria over time. (The unstated assumption is that antibiotic-resistant bacteria are harmful.)
Objective
We need to find something that Jake and Karolinka agree on. They agree that antibacterial cleaning products are effective at killing bacteria in the short term.
A
Household cleaning products with antibacterial agents kill some common bacteria.
Jake agrees with this, and so does Karolinka, so this is the point of agreement. Jake states this directly as a premise. Karolinka talks about antibacterial products producing antibiotic-resistant bacteria, which requires killing off the non-resistant bacteria.
B
Household cleaning products with antibacterial agents remove dirt better than do products lacking those agents.
Neither speaker talks about how effective antibiotic cleaning products are at removing dirt. The conversation is just focused on how the products affect bacteria.
C
The use of antibacterial agents in household cleaning products can produce antibiotic-resistant strains of bacteria.
Karolinka agrees with this, but Jake never expresses an opinion. In fact, Jake most likely disagrees, because he recommends using antibacterial cleaning products to minimize the amount of bacteria in a home. Creating resistant bacteria doesn’t sound like minimizing anything.
D
Common household bacteria are a serious health concern.
Neither speaker talks about how serious of a health concern is posed by common household bacteria. The only possible harm mentioned is when Karolinka talks about antibiotic-resistant bacteria, and even then there’s no indication of how serious a risk that would be.
E
People should use household cleaning products with antibacterial agents to clean their homes.
Karolinka disagrees, but if you look closely, Jake doesn’t express an opinion. Jake only says that if people want to minimize the amount of bacteria, then they should use antibacterial products. Also, even if Jake stated an opinion, he would probably not agree with Karolinka.
Prosecutor: Dr. Yuge has testified that, had the robbery occurred after 1:50 A.M., then, the moon having set at 1:45 A.M., it would have been too dark for Klein to recognize the perpetrator. But Yuge acknowledged that the moon was full enough to provide considerable light before it set. And we have conclusively shown that the robbery occurred between 1:15 and 1:30 A.M. So there was enough light for Klein to make a reliable identification.
Summarize Argument
The prosecutor concludes that there was enough light for Klein to make a reliable identification. He supports this with the fact that the moon was full enough to provide considerable light before it set, and that the robbery happened before the moon set.
Identify and Describe Flaw
The prosecutor assumes that there was enough light for Klein to identify the robber because the robbery happened before the moon set and the moon was full enough to provide considerable light. But just because the moon provided considerable light doesn’t mean that it provided enough for Klein to identify the robber. There could be other reasons the light wasn’t sufficient at that time, even with the nearly full moon.
A
Klein may be mistaken about the time of the robbery and so it may have taken place after the moon had set.
The prosecutor doesn’t overlook this possibility. One of his premises states that he has “conclusively shown” when the robbery took place. This fact doesn’t necessarily rely on Klein’s memory at all, because it’s already been established.
B
The perpetrator may closely resemble someone who was not involved in the robbery.
This may be true, but it doesn’t affect whether there was enough light for Klein to be able to identify the perpetrator. The prosecutor doesn’t conclude that Klein correctly identified the perpetrator, just that there was enough light for him to make an identification.
C
Klein may have been too upset to make a reliable identification even in good light.
Like (B), this may be true, but it doesn’t affect the conclusion. Even if Klein was too upset and didn’t make an identification at all, it wouldn’t impact whether there was enough light for him to be able to do so.
D
Without having been there, Dr. Yuge has no way of knowing whether the light was sufficient.
Dr. Yuge simply “acknowledged that the moon was full enough to provide considerable light before it set.” He never claims that the light was sufficient, only the prosecutor makes that claim.
E
During the robbery the moon’s light may have been interfered with by conditions such as cloud cover.
Just because the nearly full moon provided considerable light doesn’t mean that light was sufficient for Klein to make an identification. Perhaps other factors interfered with the light, making it insufficient despite the nearly full moon.