Logical reasoning PrepTest 130 · Section 4 · Question 23

Incorrect. These craters are both shorter and the same age, so it's unclear that information about this line of craters is relevant to determining the source of the other line.

Correct. Argument or Facts:
Argument

Valid or Flawed:
Flawed

Question Type:
Strengthen

Stimulus Summary:
Certain craters were likely caused by either volcanoes or meteorites.They're in a line, so they're probably not a mix of both causes. They're all different ages, so volcanoes are more likely the cause than meteorites.

Answer Anticipation:
This argument starts by noting a phenomenon—8 craters in a straight line, all from different ages. It then raises two explanations—volcanoes and meteorites—and notes that it's unlikely the craters were caused by a mix of the two. Based on the available information, the argument then concludes one of the explanations is likely correct—volcanoes.

Since this argument reaches a conclusion that explains a phenomenon, we can strengthen it by providing evidence that the explanation is likely correct or that a competing explanation is likely wrong. Here, the information that is specifically cited as leading to the author's conclusion is that the craters are of different ages. So the correct answer will likely connect that information to volcanoes, or use it to argue against meteorites.

Answer Explanation:
T his answer takes the premise that the author used to justify the conclusion that volcanoes are the source of the craters and says that it makes it unlikely that the craters were caused by meteorites (since there's no known natural way that that could have happened). By using information that has been established about the craters to show that an alternative explanation is unlikely, this answer strengthens the explanation in the stimulus.

Key Takeaway:
Arguments that conclude one explanation for a phenomenon rely on the evidence being stronger for that explanation than any alternative explanation. Whenever you're dealing with an argument that concludes an explanation, start to think about alternatives and look for answers that deal with them.

Incorrect. First, this answer choice applies equally to volcanoes and meteorites, and the argument is trying to support one explanation over the other. Second, if anything this undercuts the argument that volcanoes were the source (potentially hinting at an undefined third source of the craters).

Incorrect. This answer brings up evidence against the volcano theory, thus cutting against the argument.

Incorrect. Very tempting answer! It seems to argue against meteorites as the source of the craters. However, it's already been established that the craters are of a different age, so a single meteor shower serving as the source had already been eliminated as a possibility, and this answer therefore doesn't make it any more likely that the source of the craters is volcanic activity.