GMAT Critical Reasoning (CR) | Re: A survey of the advice given by the best-known stock market analysts

C - If he's cheap but he sucks then it's not a good idea to hire him, right?

D instead tells us that maybe he's not the best overall, but in he's an expert (98% accurate) in a certain kind of stocks, so if you want to invest in that kind of stocks it's a really good idea to hire him.
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