PrepTest 158

Perhaps this could be inferred from the argument, but this claim is never explicitly made in the passage. The author never definitively claims that radioactive elements were created when the universe began, so the author does not make a definitive statement about what happened to those elements.

Argument or Facts:
Argument

Valid or Flawed:
Flawed

Question Type:
Main Point

Stimulus Summary:
Radioactive elements may have been created when the universe began, but they're definitely being made today. Because radioactive elements are unstable and decay after a few million years, there wouldn't be any left today if the universe didn't keep making radioactive elements. And there's a lot of radioactive elements left today.

Strategy Overview:

1. Identify the conclusion
2. Identify the premises
3. Make sure the premises support the identified conclusion, and that the identified conclusion does not support anything else in the passage
4. Find the answer choice that restates the conclusion

Answer Anticipation:
There are many ways to find an argument's main conclusion on Main Point questions. We can look to terms that denote conclusions, like "so," "therefore," and "thus." We can look for "shift" words — like "however," "but," and "nevertheless" — which often accompany the main conclusion. And the presence of assertive, authorial language can provide a clue as to the main conclusion.

What can be difficult, however, is getting several statements with these features. The second sentence, which uses the "shift" word "however" and assertive language with "clearly," is a strong candidate for the main conclusion. But there are two other claims with the conclusory word "so" — the second part of the third sentence ("so most of them decay ...") and the first part of the final sentence ("So, if no new radioactive ...") — which are also conclusions.

When there are three possible main conclusions, the argument features a main conclusion and two subsidiary conclusions. To determine the main conclusion, we should remember that the main conclusion does not support anything else in an argument. So we need to figure out which statement is supported by the other two.

Between the two "so" statements —the second part of the third sentence ("so most of them decay ...") and the first part of the final sentence ("So, if no new radioactive ...") — we can determine that the second is supported by the first. And that's because "so" statements are directional — the first "so" statement will always bolster the second. The fact that radioactive elements decay after a few million years supports the claim that if no new radioactive elements were made after the formation of the universe, we'd be all out of radioactive elements. This means the second part of the third sentence has a supporting role and cannot be the main conclusion.

That leaves us with the second sentence and the first part of the last sentence as possible main conclusions. If you cannot determine which supports which, a helpful heuristic is the "Why" Test. That involves taking both conclusions and asking ourselves, "Why is the first conclusion true? Because the second conclusion." If that formation makes sense, then the first conclusion is the main conclusion. If that formation doesn't make much sense to you, try it the other way: "Why is the second conclusion true? Because the first conclusion." If that makes more sense, then the second conclusion is the main conclusion.

So let's take the second sentence and the first part of the last sentence, and apply that test: "Why is the claim that radioactive elements are still being created in the universe true? Because if no new radioactive elements were made after the formation of the universe, we'd be all out of radioactive elements." Hopefully, that formation makes sense, especially when we add in the final claim in this argument: there's an abundance of radioactive elements now. This is essentially the contrapositive, so this line of reasoning should feel familiar to us.

If the first formation didn't make sense, try it the other way. "Why is the claim that if no new radioactive elements were made after the formation of the universe, we'd be all out of radioactive elements true? Because radioactive elements are still being created in the universe." Does that make more intuitive sense to you? It seems strange and illogical to support a hypothetical about running out of radioactive elements with a claim about the presence of radioactive elements.

This means the claim that radioactive elements are still being created in the universe is the argument's main conclusion, and we should look for that in the answer choices.

Answer Choice Explanation:
As discussed in Answer Anticipation above, this answer choice refers to the argument's main conclusion. It is supported by every other claim in the argument, and it does not support anything else. Moreover, this answer choice does not distort or misrepresent the idea expressed in the argument's main conclusion. So this is the correct answer.

Key Takeaway:
The "Why" Test can be a helpful exercise when you've identified two or more potential main conclusions. The "Why" Test involves taking both conclusions and asking ourselves, "Why is the first conclusion true? Because the second conclusion." If that formation makes sense, then the first conclusion is the main conclusion. If that formation doesn't make much sense to you, try it the other way: "Why is the second conclusion true? Because the first conclusion." If that makes more sense, then the second conclusion is the main conclusion.

As discussed in Answer Anticipation above, this answer choice refers to the argument's second subsidiary conclusion. It is supported by the first subsidiary conclusion (the second part of the third sentence), but it supports the argument's main conclusion.

This refers to a concession the author makes at the beginning of the argument. The argument does not try to prove anything about the creation of radioactive elements during the universe's formation, so this answer choice has no role in the argument.

As discussed in Answer Anticipation above, this answer choice refers to the first subsidiary conclusion. This claim supports the second subsidiary conclusion (the first part of the last sentence), which in turn is used to support the argument's main conclusion.