Logical reasoning PrepTest 116 · Section 3 · Question 19

Incorrect. Different diseases today that target only a few strains could still devastate the food supply even if other crop diseases devastated it in the past.

Correct. Argument or Facts:
Argument

Valid or Flawed:
Flawed

Question Type:
Weaken

Stimulus Summary:
Fewer strains of a given crop are planted now than a few generations ago, so a disease today could devastate the food supply that wouldn't have in the recent past.

Answer Anticipation:
This argument makes a prediction about what would happen, and those are always suspect. Something could change in the future, especially in response to one change, that could alleviate or prevent the effects.

Here, the conclusion is particularly extreme—the food supply would be devastated" today, when it would have survived in the recent past. Anything that calls that into question—any other change made as the crop diversity has decreased—would weaken that prediction.

Answer Explanation:
This answer establishes something that would mitigate the devastation—the crops could quickly be replaced with other strains, ones that aren't affected by a disease that strikes "only a few strains." This answer therefore weakens the argument.

Key Takeaway:
Always think about alternatives. And when an argument makes a prediction about what would happen if one event/change occurred, then start thinking about other things that might mitigate that.

Incorrect. While this answer is too weak to have much of an impact on the argument, if it were stronger, it would align with the conclusion and thus strengthen the argument.

Incorrect. With that last clause, this answer invalidates itself. If crops were now just a minor part of the food supply because of a more varied diet, then that would call into question the devastat[ion]" to the food supply from a crop disease. However, if crops are still relied on heavily, then there could be devastation to the food supply from such a disease.

Incorrect. While this may make the crops more likely to resist certain threats, the argument is about the threat from disease, and this answer doesn't establish anything about the ability of crops to resist those, so it doesn't affect the argument.