Explanation

Yes, would appreciate an explainer on the difference between c and e

@Alix-Hirsh and @Kanyin, Happy to help. In the argument, Mr. Moltz doesn't look to be thinking the arguments supporting alien life are good. There are supposedly many stars and planets in space that could support alien life, but based on Moltz's facts, astronomers have not detected a single one of these planets outside of our solar system. He then concludes that no detected planet means no alien life, which means that life only exists here on Earth. Moltz's strongest evidence for the lack of alien life is that astronomers have failed to discover any planets outside of our solar system. However, even if astronomers haven't detected any other planets, this doesn't mean that those planets do not exist. It's possible that we simply haven't found these planets yet. Because this is a weaken question, we are likely looking for something that draws evidence to the logical fallacy present in Moltz's argument (that a lack of evidence is proof that something doesn't exist). Let's take a look at (C) and (E). (C) says, "Detecting planets outside our solar system requires more sophisticated instruments than are currently available." (C) does a great job at pointing out the flaw in Moltz's argument (that a lack of evidence proves that something doesn't exist). Just because we have not yet found planets outside of our solar system does not mean that they do not exist. If we do not yet have sophisticated enough instruments to detect them, it's possible that they're actually out there. (C) works by suggesting that Clay's evidence is irrelevant to his conclusion. Thus, (C) is the correct answer choice. (E) says, "Due to sheer distances and expanses of space involved, any extraterrestrial civilization would have great difficulty communicating with ours." In reading the stimulus, we see that the question at hand is about the existence of aliens. It is not about whether or not humans can communicate with them. While this topic could be relevant to a similar question, communication with extraterrestrial civilizations—or a lack thereof—will not really tell us about whether or not those civilizations exist. Thus, we can get rid of (E). Does this make sense? Let us know if you have any more questions!

Hi! Could you help me answer why (D) is wrong and what exactly the answer is saying. Thank you!

@ijchoi793, Let's take a look at (D). (D) says, "The soundness of the conclusion reached by applying a mathematical model depends on the soundness of the assumptions on which the model is based." The topics (D) discusses, math and assumptions, are definitely relevant to the astronomer's argument. However, the problem with (D) is that Clay's conclusion isn't reached by applying a mathematical model. Therefore, (D) doesn't weaken Clay's conclusion, so we can get rid of this answer choice. Hope this helps. Let us know if you have any other questions!