Logical reasoning PrepTest 109 · Section 3 · Question 10

Incorrect. This answer is too strong in talking about "all" wavelengths that can cause any eye damage. The stimulus specifically discusses "severe" eye damage and it leaves open the possibility that all wavelengths of light have some chance of damaging eyes while the ones blocked out by the ozone layer are particularly damaging.

Incorrect. The stimulus never discusses the distribution of animals on the planet. We know that "many" species are threatened by these holes which isn't strong enough to tell us that "few" species aren't so threatened.

Incorrect. The stimulus does say that holes in the ozone layer threaten the eyes of "many" species but that doesn't let us say that some species have eyes impervious to unfiltered sunlight. It's possible that those species (if there are any—"many" could be all) aren't threatened because they don't have eyes or they live in caves or they live in an area that doesn't have a hole in the ozone above it.

Incorrect. The stimulus notes that the ozone layer blocks out multiple wavelengths, so it could be the case that the severe damage is caused by the combination of multiple wavelengths instead of a single one.

Correct. Argument or Facts:
Facts

Question Type:
Must Be True

Stimulus Summary:
Ozone layer — Filters all of some wavelengths out, lets others through
This is how it helps land animals
Holes in the layer are dangerous, including that they can lead to eye damage

Answer Anticipation:
This stimulus revolves around two key concepts—the role of the ozone layer, and the dangers that sunlight poses to terrestrial animals. Both of these ideas are causal—they talk about the effects of the ozone layer, holes, and certain wavelengths of light. What are the causes and effects specifically?

In general, the ozone layer is blocking out many wavelengths of light, which is why it's "important" to terrestrial animals. How are they important?

Since the next line after that importance is introduced is about how holes in the ozone layer have dangers associated with them it must be the case that the wavelengths of light pose dangers to these animals. And then a specific danger is brought up—severe eye damage.

Putting this all together we can infer that certain wavelengths of light that the ozone layer blocks can cause severe eye damage in animals. Let's see if there's an answer in that general area.

Answer Explanation:
This answer brings all the statements from the stimulus together. Since the ozone blocks out some wavelengths of light and holes pose a danger to eyesight it must be the case that the holes make it more likely that these wavelengths make it to the eyes of animals.

Key Takeaway:
Causal statements in the stimulus of Must Be True questions can build together to lead to inferences. Always pay attention to them when they show up!