Why is answer choice D incorrect?

@Samantha-Alexis, Great question. Let's look at (D). (D) says, "How bright celestial objects appear to be depends on how far away from the observer they are." You're right—(D) just restates something that we already know, so there's no way that it can do anything for us. (C) says, "The brighter a star is, the younger it is." We know from the stimulus the stars are brighter, and if brighter stars mean younger stars, then we don't necessarily have the paradox of there being stars that are older than the universe, so (C) helps to explain why the astronomer's estimates of the stars' distances from Earth help resolve the earlier conflict between the ages of these stars and the age of the universe. Thus, (C) is the correct answer choice. Does this answer your question? Let us know if you'd like more clarification!

Doesn't question D incorrectly reverses the premise brought forth in the stimulus?

Can't type. Doesn't question D incorrectly reverse* the premise brought forth in the stimulus?

@dace, No, (D) actually restates what's told to us in the second to last sentence, which is a premise. We're told there that "the farther away the stars are, the greater their intrinsic brightness must be, given their appearance to us on Earth." (D) paraphrases this. Does this make sense? Let us know if you have any other questions!