#10 - Radioactive elements may have been created when the universe began.

[Jeremy Press]

Complete Question Explanation

Main Point. The correct answer choice is (B).

The stimulus makes an argument about whether radioactive elements are still being created in the universe. The author begins with an acknowledgment that there is a possibility radioactive elements were created when the universe began. The author then qualifies that first assertion, adding their own commentary that they want the reader to know and believe, that "these elements are clearly still being created in the universe today." Notice the use of the term "clearly," which is a very common indicator of a conclusion in LSAT arguments.

The remainder of the stimulus supports the author's conclusion that radioactive elements are still being created. The author argues based on the instability of radioactive elements and their tendency to decay relatively quickly, observing that if radioactive elements had not been created after the universe began, there would not be any left in the universe today, when in fact we can observe an abundance of radioactive elements still in the universe today.

The basic structure of the argument is thus as follows:

Sentence 1: Background assertion
Sentence 2: Main Conclusion
Sentences 3-4: Premises

Since this is a Main Point question, we need only to find the answer choice that either directly restates or closely paraphrases Sentence 2 of the stimulus.

Answer choice (A): Answer choice A states material that is used to support the conclusion that radioactive elements are still being created, i.e. material that is part of the premises of the argument, thus it is incorrect.

Answer choice (B): This is the correct answer choice. Answer choice B is an accurate paraphrase of Sentence 2 of the stimulus, which we have identified as the argument's main conclusion, thus it is correct.

Answer choice (C): Answer choice C is part of sentence 4 of the stimulus, which is part of the support for the conclusion that radioactive elements are still being created. Thus, it is not the main conclusion. Do not be distracted by the word "so" at the beginning of sentence 4. Sentence 4 is a subsidiary (or intermediate) conclusion of the argument. A subsidiary conclusion has some support given for it (in this case, Sentence 4 is supported by the prior sentence's facts that radioactive elements are unstable and decay relatively quickly), but it is also used to support the argument's main conclusion (i.e. since if no new radioactive material were being created it would all be gone," but we know there are still radioactive elements in the universe, there must still be new radioactive elements being created).

Answer choice (D): Answer choice D is background information asserted in the first sentence, but it is not part of the argument proper (i.e. it's neither a premise supporting the main conclusion, nor is it the conclusion the author wants us as readers to believe). Thus, it is incorrect.

Answer choice (E): Answer choice E is part of Sentence 3, which supports the argument's main conclusion. Again, do not be distracted by the "so," which in this case indicates another subsidiary conclusion. Since this statement does contribute to supporting the conclusion that new radioactive elements are being created, it is not the main conclusion and the answer is thus incorrect.

[angelsfan0055]

Hi! would love an explanation on this one. I picked C, but had some difficulty

[Beth Hayden]

Hi Angels Fan,

This is a main point question, so the first thing you want to do is find the conclusion. Each argument is going to consist of a conclusion and premises that are used to support that conclusion. Ask yourself, which statement is the rest of the argument trying to prove?

The conclusion of this argument is that radioactive elements are still being created in the universe today (they weren't just created when the universe began). The reasoning is that the elements are unstable and decay after a few million years, and the universe is presumably much older than that. So if all radioactive elements were created when the universe began, they would have all decayed by now and there wouldn't be any left. But there are a bunch of radioactive elements right now. Thus, those elements must have been created afterward.

Answer choice (B) nicely sums up the conclusion--every other sentence is a reason why the author believes that radioactive elements are still being created.

Answer choice (C) is true, but it's a premise, not a conclusion. (C) is a reason why the conclusion in (B) is true, it's not the conclusion itself. In fact, all four of the wrong answer choices in this question are premises which help prove (B).

One trick I like to use to confirm I've found the conclusion is see if I can add the word "because" after the answer. Here, the statement in (B) is true because the statements in (A), (B), (D), and (E) are true.

Hope that helps!
Beth