PrepTest 140, Section 1, Question 9
Records from 1850 to 1900 show that in(52 more words not shown)
The argument proceeds(1 more words not shown)
- Ainferring from a(15 more words not shown)
- Binferring from the(20 more words not shown)
- Cinferring from records(12 more words not shown)
- Dinferring from records(21 more words not shown)
- Einferring the existence(21 more words not shown)
Reading the argument
A good harvest followed by heavier babies sounds like a pattern worth investigating. Perhaps more food was available to pregnant mothers, and that affected their babies. It's a plausible story. Now notice how the argument moves from the pattern to that story.
The records concern crop success and birth weight. The conclusion concerns food available to a particular mother and the health of her baby. Those ideas are related, but they aren't identical. A successful regional harvest doesn't itself tell us exactly what a mother could obtain, and birth weight isn't simply another name for health.
What we’re looking for
The question asks us to describe the argument's method. We don't need to resolve those concerns or prove the explanation false. We need to track the move: two things varied together, and the author uses that correlation to claim a causal connection between two related but different things. Keep all four terms straight when matching the choices.
Working the answers
- ACorrect
The claimed correlation links successful crops with higher birth weights. The causal claim links food available to the mother with the newborn's health. That's why the answer says “two other phenomena”: the conclusion changes the terms instead of merely announcing that crops cause birth weight. A captures both the correlation-to-cause move and that change.
- B
The conclusion says food availability matters to a large extent, not that it is the only cause of a newborn's health. Other influences could still matter. “Sole cause” therefore goes beyond the argument, and the conclusion also uses different terms from the original correlation.
- C
The dates identify the records used as evidence. The argument isn't simply saying that the same two recorded quantities still vary together today. It draws a causal conclusion about maternal food availability and newborn health. C misses that move.
- D
A common cause would be a third factor that produced both outcomes—for example, some factor responsible for both better crops and higher birth weights. The author doesn't propose such a factor. The argument instead takes the observed association as evidence of a causal connection involving food and health.
- E
The starting evidence is a correlation, not an already established causal connection. The author doesn't begin with one known cause-and-effect relationship and use it to derive a second, then explain both. That description supplies a kind of evidence the passage never gave us.
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