"Surprising" Phenomenon
Most people who ate seafood at a restaurant didn’t come into contact with the offending bacteria, yet health officials are certain the bacteria caused several cases of illness.
Objective
The right answer will be a hypothesis that explains how health experts can be certain the bacteria caused the illness, despite most people who ate seafood at the restaurant not coming into contact with the bacteria. The explanation must result in only the people who ended up getting sick coming into contact with the bacteria.
A
Most people are immune to the effects of the bacteria in question.
We need something that tells us about the people who ended up getting sick. This tells us about most people in general.
B
Those made ill by the bacteria had all been served by a waiter who subsequently became ill.
Did the waiter come into contact with the bacteria? Did the waiter get sick because of the bacteria, or for some other reason? Besides, we already know the bacteria was carried by contaminated seafood.
C
All and only those who ate contaminated seafood at the restaurant on that date were allergic to the monosodium glutamate in a sauce that they used.
This doesn’t explain why health experts are confident the bacteria was the problem. This simply gives another reason some people might’ve fallen ill.
D
The restaurant in question had recently been given a warning about violations of health regulations.
We already know the restaurant is serving contaminated food. We don’t need to double down.
E
All and only those who ate a particular seafood dish at the restaurant contracted the illness.
Why did only some, but not all, people who ate seafood at the restaurant fall ill? Because those people who fell ill all ate a contaminated seafood dish that carried the bacteria.
Summarize Argument
The author concludes that we should expect an overall decrease in the negative environmental effects of acid rain. This is because the amount of acidic pollutants released into the air has decreased over the last several decades, and negative environmental effects of acid rain are caused by these pollutants.
Notable Assumptions
The author assumes that there haven’t been other changes over the last several decades that increase the negative environmental effects of acid rain.
A
Some ecosystems have developed sophisticated mechanisms that reduce the negative effects of increased levels of acids in the environment.
If anything, this might strengthen the argument by giving us reason to think at least some ecosystems have additional new protections that can reduce harm from acid rain.
B
The amount of acid-neutralizing buffers released into the air has decreased in recent years.
This indicates that certain things that protect against acid (acid-neutralizing buffers) have decreased, which would tend to increase harm from acid rain. This increase might offset the effect of decreased acidic pollutants.
C
The current decrease in acidic pollutants is expected to end soon, as more countries turn to coal for the generation of electricity.
This suggests that the decrease in acidic pollutants will end, which implies that we should not expect harm from acid rain to decrease in the near future. Once pollutant levels stop decreasing, we would expect harm from acid rain not to decrease.
D
The effects of acid rain are cumulative and largely independent of current acid rain levels.
This suggests that decreased amounts of pollutants in acid rain don’t significantly impact the harm caused by acid rain. Thus, we have less reason to think that decreased acidic pollutants would lead to less harm.
E
The soils of many ecosystems exposed to acid rain have been exhausted of minerals that help protect them from acid rain’s harmful effects.
This suggests that protections against acid rain have decreased, which would tend to increase harm from acid rain. This increased harm might offset the benefit of decreased acidic pollutants.