Self-study
By dating fossils of pollen and beetles, which returned after an Ice Age glacier left an area, it is possible to establish an approximate date when a warmer climate developed. ██ ███ ███████ █████ ██ ███████ ████ ███ ██████ ██████ ████ █ ████ ███████ █████████ ███████████ █████ ███ ███████ ██ ███ ████████ ████ ███ ██████ ███████ ████████ ██ ███████ ████ ███ ████ ███████ ███ ███ ███████ █████ ████ █████ ███ ███████ ████████████
Structure: Surprising Phenomenon
The stimulus gives us a general rule: dating fossils of pollen and beetles can allow us to establish an approximate date for when a warmer climate developed after an Ice Age glacier left. We're then told about an unusual phenomenon: in one case from a glacial area, the insect record suggests that a warmer climate developed much earlier — immediately after the glacier melted — than the pollen record indicates.
Analysis: Potential Ways to Resolve
We're looking for a way to resolve the apparent discrepancy between the dates suggested by the insect record and the pollen record. The answer choices that succeed in this will likely present additional facts that we're not yet aware of: maybe insects were able to move back into the area even before the climate became warm enough for pollen to be present, or maybe for some reason the earlier pollen fossils weren't preserved. There is plenty of information that could help explain the apparent discrepancy. For this question, we want to find the one answer choice that does not do this.
12.
Each one of the following, ██ █████ █████ ██ ███████ ███ ████████ ███████████ ███████
a
Cold-weather beetle fossils ███ ██ ████████ ███ █████ ██ ███████ ████ ████ ██ ████ █████████
This information helps resolve the apparent discrepancy by suggesting that the reason the insect record appears to suggest an earlier development of a warm climate is that some of the earlier insect fossils might actually be cold-weather beetles that have been mistaken for warm-weather ones. Because (A) helps resolve the tension in the stimulus, it isn't the answer choice we're looking for.
b
Warm-weather plants cannot █████████ ██████████ ██ ███████ ██ ███ ███████ ██ █ ███ ████████████
This also explains the apparent discrepancy by explaining why there is an apparent "lag" between the pollen record and the insect record: beetles can generally establish themselves faster in a new environment than warm-weather plants can. (B) also isn't what we're looking for.
c
Beetles can survive ██ █ ██████████ ██████ ███████████ ████ ██ ███████████
(C) also explains why the pollen record is behind the insect record. Beetles were able to move into the area immediately after the glacier melted and survive by scavenging, even when there weren't pollen-bearing plants around. (C) explains why beetles were present in the area before pollen-bearing plants, so it isn't the answer choice we want.
d
Since plants spread ████████ ██ █ ███ ████████ ███████████ ███ ███████ ████ ██ ███ ██████ ██████ ██ ████████ ██ ██ ███ ███████ ███████
This isn't what we're looking for either. (D) also helps resolve the apparent discrepancy by suggesting that the apparent "lag" in the pollen record compared to the insect record might just be a gap due to the uneven spread of plants, which researchers have mistakenly interpreted as indicating that plants were absent up to a certain point.
e
Beetles are among ███ ██████ ██████ ███████ ███ ███ ████ █████ ████ ████ ████████████ ███████
This doesn't help resolve the discrepancy. If you thought it did, you might have assumed that since beetles are older than many warm-weather plants, maybe the reason the insect record goes back further than the pollen record in this case is that beetles existed when the glacier melted, whereas warm-weather plants didn't.
But this answer choice only talks about "many" warm-weather plants, not all pollen-bearing plants. The stimulus certainly suggests that at least some pollen-bearing plants and beetles did exist at the same time, at least after the Ice Age, so that we can use them both to date when a warm climate developed after Ice Age glaciers departed. Knowing that beetles are one of the oldest insect species and happen to be older than some warm-weather plants doesn't help us explain the discrepancy between the insect record and the pollen record in this specific case.