In an experiment, some volunteers

Answer choices

1. A

   Too Strong: fully11% picked this

   Three months is enough time for the body to fully benefit

   In order for the author's story to be plausible, she does have to assume that "3 months is enough time for the body to benefit from aerobic exercise", because if it isn't enough time, then the aerobics class can't be the reason that the people in the aerobics group had less stress. But she doesn't need to assume that 3 months is enough for 100% of the benefits. Even if these people only had 90% of the benefits, that could still work for her story.

   11%
2. B

   Irrelevant Distinction31% picked this

   The volunteers who were assigned to the aerobics classes did not also lift weights

   If the aerobics people did also lift weights outside of class, that wouldn't weaken the argument. It's not like we'd be able to say, "Hey, author, maybe it was the weight-lifting they did, not the aerobics class, that made them have less stress". That would be a nonsensical alternative explanation because the weight-lifting group obviously did weight-lifting, so if weight-lifting were the thing leading to lower stress then the weight-lifting group would have had comparable stress, not more stress.

   31%
3. C

   Irrelevant Distinction6% picked this

   On average, the volunteers who were assigned to the aerobics classes got more exercise in the months in which they took those classes than

   The author doesn't have to assume anything about "total exercise" for the aerobics group during the study vs. prior to the study. It wouldn't hurt the author if the aerobics group, prior to the study, go the same or more exercise as they did during the study. All the author needs to assume is that the aerobics group got more aerobic exercise during the study than the weight-lifting group did.

   6%
4. D

   Weakens13% picked this

   On average, the volunteers assigned to the aerobics classes found it less difficult to perform the mathematical calculation than did the volunteers

   This is the opposite of what we want. If this answer said, "on average, the aerobics people did not find it less difficult to do the math problem", we'd happily pick it. This answer as written is giving an Alternate Explanation for why the aerobics people had less stress. The author is assuming that the aerobics people found the math problem just as hard as the weight-training people did, but because of their (presumably) higher level of aerobics exercise (and because of the supposed idea that aerobic exercise helps the body handle stress), they showed less measurable stress symptoms.

   13%
5. E

   Correct38% picked this

   On average, the volunteers assigned to the aerobics classes got a greater amount of aerobic exercise overall during the experiment, including any exercise outside

   Why this is right

   If we negate this, it would weaken the argument. It would be saying, "the people in the aerobics group did not get more aerobic exercise during the study than the weight-training people did". That would blow up the plausibility of the Author's Explanation. The author is pitching "aerobic exercise" as the causal difference-maker that accounts for the lower stress symptoms of the aerobic group. But in order for some factor to explain the difference between two groups, it needs to actually be a difference between the two groups. If Jack got a 150 and Jill got a 160 on her LSAT, we can't say that "Jill's higher score was due to the fact that she read Logic Master", if Jack also read Logic Master.

   Skill tested: Necessary Assumption · how this choice captures the argument's function is the move to repeat next time.

   38%