LSAT Explanation PT 19, S2, Q4: Scientists analyzing air bubbles that had

LSAT Question Stem

Which one of the following, if true, would most seriously undermine the scientist's hypothesis? 

Logical Reasoning Question Type

This is a Weaken question. 

Correct Answer

The correct answer to this question is D. 

LSAT Question Complete Explanation

First, let's analyze the argument in the passage. The scientists find that the ice-age atmosphere contained unusually large amounts of ferrous material and surprisingly small amounts of carbon dioxide. They know that algae absorb carbon dioxide from the atmosphere. Based on this information, they hypothesize that the ferrous material promoted a great increase in the population of Antarctic algae, such as diatoms. The conclusion of the argument is this hypothesis.

Now, let's create an "Evaluate" question about the argument: "Is there evidence of an increase in the population of Antarctic algae, such as diatoms, during the ice age?"

This LSAT problem is a Weaken question type, which means we are looking for an answer choice that would most seriously undermine the scientist's hypothesis.

Let's analyze each answer choice:

a) Diatoms are a microscopic form of algae that has remained largely unchanged since the last ice age.

- This answer choice doesn't address whether the population of diatoms increased during the ice age, so it doesn't weaken the hypothesis.

b) Computer models suggest that a large increase in ferrous material today could greatly promote the growth of oceanic algae.

- This answer choice actually supports the idea that ferrous material could promote algae growth, so it doesn't weaken the hypothesis.

c) The dust found in the air bubbles trapped in Antarctic ice contained other minerals in addition to the ferrous material.

- This answer choice doesn't provide any information on whether these other minerals affected the population of Antarctic algae. It doesn't weaken the hypothesis.

d) Sediment from the ocean floor near Antarctica reflects no increase, during the last ice age, in the rate at which the shells that diatoms leave when they die accumulated.

- This answer choice directly undermines the hypothesis by providing evidence that there was no increase in the population of diatoms during the ice age. This is the correct answer.

e) Algae that currently grow in the oceans near Antarctica do not appear to be harmed by even a large increase in exposure to ferrous material.

- This answer choice doesn't address whether the population of algae increased during the ice age. It doesn't weaken the hypothesis.

In conclusion, the correct answer is D, as it provides evidence that there was no increase in the population of diatoms during the ice age, which undermines the scientist's hypothesis that the ferrous material promoted a great increase in the population of Antarctic algae.