PrepTest 127

Incorrect. There's no discussion of sunscreen use, just what it protects against, so this answer is out of scope.

Incorrect. While the argument does establish UV-A as a source of premature wrinkles, it doesn't say that it's the only or even the primary cause of such wrinkles, so this answer is unsupported.

Incorrect. Just because sunscreen didn't protect against wrinkling doesn't mean that it wasn't known that UV-A rays caused it. Additionally, this answer is about "[t]he" cause of premature wrinkling, and the stimulus establishes only that UV-A rays are a cause.

Incorrect. The change noted in sunscreen formula is in its protection against UV-A—the wrinkle-inducing rays—not UV-B, so there's no indication that it protects better against sunburn.

Correct. Argument or Facts:
Facts

Question Type:
Must Be True

Stimulus Summary:
The sun emits:
(1) UV-A - Causes wrinkles
(2) UV-B - Causes sunburn

Until 10 years ago, sunscreen protected against UV-B but not UV-A.

Answer Anticipation:
The first sentence and the second sentence both talk about two types of UV radiation emitted by the sun, so it's possible to combine them to form an inference.

Putting together the effects of the radiation with the information about sunscreen, we can infer that, until 10 years ago, sunscreen protected against sunburn but not wrinkles. Let's find an answer that aligns with that.

Answer Explanation:
Since sunscreen didn't protect against UV-A—the "wrinkle rays" as we're calling them—until 10 years ago, before that, people who spent the same time in the sun as others should be just as likely to have such wrinkles whether or not they slathered the sunscreen on.

Key Takeaway:
Must Be True questions ask you to make inferences. Much like in Logic Games, inferences are generally derived by combining statements that talk about the same thing. Always look for overlapping statements in a Must Be True stimulus!