“知之为知之，不知为不知，是知也”的恰当英文翻译是（ ）。

A、When you know a thing, to hold that you know it. When you do not know a thing, to allow that you do not know it. This is knowledge.;
B、When you know a thing, to recognize that you know it, and when you do not know a thing, to recognize that you do not know it. That is knowledge.;
C、If you know it, say you know. If you don’t know it, say you don’t. That is knowledge.;
D、When you know a thing, say that you know it; when you do not know a thing, say that you do not know it. It is wise doing so.