LSAT 156 | Section 2 | Logical Reasoning: Q14

LR Question 14 Explanation

QUESTION TEXT: When polar ice caps grow (during ice ages, for example), lighter …

QUESTION TYPE: Most Strongly Supported

FACTS:

1. When ice caps grow, heavy oxygen in the ocean increases, and marine organisms absorb it.
2. When ice caps shrink, the heavy oxygen in the ocean decreases.
3. In a 30,000-year period, concentration of heavy oxygen in the sea increased for 20K years and then decreased for 10K years.

ANALYSIS: We have an explanation then an example. All we need to do is map the explanation to the example. If heavy oxygen was increasing, the ice caps must have been growing during that time. When heavy oxygen starts decreasing, that means the ice caps started shrinking.

So the simplest explanation is: growth for 20,000 years, then shrinkage for 10,000 years.

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1. We don’t have any info about exact temperatures.
2. This is unsupported. We don’t know how much they grew or shrunk, so it could go either way really. If anything, since they grew longer than they shrunk, we’d have reason to believe the opposite.
3. Ice ages are just one example of growing ice caps.
4. CORRECT. This directly matches the pattern of oxygen levels described.
5. It would be the opposite. If ice caps were shrinking, oxygen would be decreasing, not increasing.