PT145.S2.Q4

PrepTest 145 - Section 2 - Question 4

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The northern cardinal, a nonmigratory songbird, was rare in Nova Scotia in 1980; the province was considered to be beyond that bird's usual northern range. ██ █████ ████████ █████ ████████████ █████████ ████ ████████ █████████ ████ █████ ██████ ██████ ███ ███████ ██████ ███████████ ████ ████████ ████ ████ ███████ ██ ██████ ███████ ███ ████████ ███████████ ███ ███ ████████ ██████████ █████████████ ██ ████ ███████

Summarize Argument: Phenomenon-Hypothesis

The author starts by observing a correlation: from 1980 to 2000, the range of the northern cardinal expanded northward to include Nova Scotia. In the same period, average winter temperature rose slightly. The author offers a causal hypothesis to explain the phenomenon of the northern cardinal's expanding range: warmer winters probably caused the cardinal's range to expand.

Notable Assumptions

The author infers causation from correlation: winter temperatures rose at the same time the cardinal's northern range was expanding, so warming temperatures must have caused the expansion. Thus, the author assumes there’s no third factor, unrelated to warmer winters, that could have allowed the cardinals to thrive in Nova Scotia. The author also assumes that cardinals' range depends at least in part on winter temperatures — i.e., that cardinals are sensitive enough to winter temperatures that the slight increase was enough to allow them to live in Nova Scotia. A good way to weaken the argument would be to show that one of these assumptions is invalid, thus undermining the author's causal hypothesis, or by proposing an alternative explanation for why the cardinal's range expanded in this period.

Show answer
4.

Which one of the following, ██ █████ ████ ███████ ███ █████████

a

Bird feeders, an █████████ ██████ ██ █████████ ██ █████████ ██████ ██████ ███ ████ ██████ ██ ████ ██████ █████ █████

This weakens the argument by providing an alternative explanation for why cardinals expanded into Nova Scotia. Instead of warmer winter temperatures, it might have been the increased availability of food in winter, thanks to more bird feeders being available, that allowed cardinals to proliferate in Nova Scotia.

Alternate explanation
90%
b

Because of their ███ ████████ ████████ █████████ ███ ██████ ██ ████ ████ ████ █████ ████████ ███████ ████

Irrelevant. This answer choice might be suggesting that northern cardinals are more vulnerable to predators than other birds are. But having this information doesn't help us evaluate whether warmer winters allowed them to proliferate in Nova Scotia or not.

Failed alternate explanation
2%
c

Some songbird species █████ ████ ███ ████████ ████████ ████ ██████ ████ ██████ ███████ ████ ███ █████

This answer choice is perfectly compatible with the author's conclusion: perhaps warmer winters benefited the other songbirds as well. We’re trying to weaken the link between warmer winters and increasing cardinal populations.

Failed alternate explanation
1%
d

According to field █████████████ ███ ███████████ ██ █████████ █████ ██████████ ████ ██████ ███ ██████ ████ ████ ██ ████ ████ ███ ███████████ ██ ████████████ ██████

Irrelevant. For one thing, we have no idea if these field observations were based in Nova Scotia. We're also only interested in the northern cardinal, which is a nonmigratory songbird, so knowing about migratory birds doesn't help us weaken the argument.

Failed alternate explanation
3%
e

Birds that prey ██ █████████ ██████ ████ ██████ ██ ████ ██████ ███████ ████ ███ █████

Irrelevant. It's possible that the warmer winters allowed these predatory birds to expand their ranges, too, or that they moved north in response to the increasing cardinal population. This answer choice doesn't weaken the claim that warmer winters allowed northern cardinals to thrive in Nova Scotia in the first place.

Illusory inconsistency
4%

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