Terminology – What Can I Assume When Examining Computer Science AP?

I plan to take the Computer Science AP exam in May and I'm trying to practice using standard questions. I used Barron's practice test and came across this question:
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As a regular Java user, inheritance has not been a confusing topic for me, but the answer to this question really troubles me. While I knew that A was correct, C should also be. The point of private members is only accessible in a class. Of course, you can use accessors, but the member is not accessible in itself, which the option seems to indicate. If I can just say that accessors can be used, why should we consider the privacy of members? So, my general question is: what can I safely assume on the AP CS exam? Will questions like this come up? I know this is not the best forum to ask questions about this, but the only other way I could find is CollegeConfidential, which crashed after trying to sign up.