<p>It completely depends on the target colleges. The bulk of US colleges place no to extremely little emphasis on ECs, mostly admitting students based on GPA/Transcript/Test scores.</p>
<p>Case C probably has the best chance at a prestigious college, assuming their grades are stellar as well. Case A probably has nice grades, but a slim chance due to their lack. Colleges can see that B is just fluffing their application. Basically, A and B should be looking at state colleges. C would have the best chance somewhere prestigious. </p>