Here's the explanation of answer (B) given at the top of this thread:
"Answer choice (B): This is the correct answer choice. If, as this choice provides, the majority of the sales reps at the company fall under the category of “engineering degree but no previous experience,” then that in itself might explain why most of the company’s successful sales representatives fall under that same category (rather than the author’s assertion, that membership in this category makes one more likely to become a successful sales rep)."
Regarding your comment,
You guys realize that your explanation to this problem is misleading, right? Especially the "official" explanation, which is lousy af. There is no fallacy of overgeneralization here.
It wasn't entirely clear to me why there is a problem with the explanation, given that it doesn't discuss a fallacy of over generalization. As I read it, the original explanation seems to give an accurate description of why answer (B) would weaken the argument. As such, it's worth clarifying, since you go on to write,
I shouldn't be the one telling you this, but this is a false correlation-to-causation problem. ...He's assuming that these qualifications are the cause for why some people rise to the top. What does this conclusion also assume? At the very least, a correlation between performance and credentials.
We don't know that the company president in this problem is improperly moving from seeing a correlation to concluding that a causal relationship. Rather, all we know is that the company president observes two features (engineering degree + little to no sales experience) in the company's best sales representatives, and concludes that the company should target those features in new hires.
(B) rules out the possibility that only a small proportion of the people the company had hired possessed the features (1) engineering degree (2) little to no sales experience. If only a small fraction did have (1) and (2), and these employees were also the best sales representatives, that would strengthen the argument. By contrast, (B) is saying that most of the people the company has hired had features (1) and (2), so it shouldn't be surprising--from that pool of employees--that the "best sales representatives" also had (1) and (2). Thus (B) weakens the company president's conclusion that people with (1) and (2) should be favored in the hiring process.