PrepTest 131, Section 1, Question 12
The number of different synthetic chemical compounds that(52 more words not shown)
The reasoning above is most(12 more words not shown)
- Athe rise in(14 more words not shown)
- Bthe rise in(16 more words not shown)
- Csome synthetic chemical(13 more words not shown)
- Dpeople undergo significantly(14 more words not shown)
- Epeople can vary(10 more words not shown)
Reading the argument
“Carcinogenic” means capable of causing cancer. But knowing that a substance is carcinogenic still leaves a practical question: how much of it are people exposed to? A substance's existence somewhere is different from people regularly encountering it.
The author counts different kinds of compounds. There are relatively few known synthetic carcinogens used in pesticides, preservatives, or food additives, compared with the many nonsynthetic ones found in plants and animals. That does not tell us which group people encounter more often or in greater amounts.
Imagine a carcinogenic substance in a tree deep in Alaska or the Amazon that most people never touch. Compare it with a synthetic carcinogen in something people buy at the grocery store and eat every day. There could be many kinds in the remote forest and only a few in everyday products, yet the everyday products could account for much more human exposure.
What we’re looking for
That is the possibility the argument needs to consider before dismissing synthetic carcinogens as a cause of the rising cancer rate. For the flaw question, I would look for a distinction between how many types exist and how much exposure people actually receive.
Working the answers
- A
Increased exposure to nonsynthetic pollutants would offer a different explanation for the rise. That does not expose the argument's mistake in dismissing synthetic carcinogens. We need a reason its comparison fails to rule out synthetic causes, not another proposed cause pointing away from them.
- B
A cause other than increased exposure to carcinogens would likewise give us another account of the rise. It does not challenge the author's dismissal of synthetic carcinogens on the basis offered. The problem we identified concerns exposure to the compounds, not whether a wholly different cause might exist.
- C
Other kinds of toxicity do not answer the question about cancer. A synthetic chemical might cause skin lesions or another health problem without explaining a rise in the cancer rate. Those harms could matter in another discussion, but C does not identify the relevant gap here.
- DCorrect
People could have much less exposure to nonsynthetic carcinogens than to synthetic ones, despite there being more kinds of nonsynthetic carcinogens. A large number of compounds we rarely encounter does not make a smaller number of frequently encountered compounds harmless. D shows why the count does not justify ruling out the synthetic compounds as a cause of the increase.
- E
Different people could have different susceptibility to cancers caused by nonsynthetic compounds. That does not establish which kind of carcinogen people encounter more, nor does it show why synthetic compounds could be responsible for the recent rise. Variation among individuals does not resolve the missing exposure comparison.
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