In the following question, out of the four alternatives, select the alternative which best expresses the meaning of the idiom/phrase.
It's not rocket science

Options

A. A task so difficult that it has a slim chance of success.
B. Speak in jargon that is not understandable by laymen.
C. Used to say that you do not think that something is very difficult to do or to understand.
D. Refuse something that someone wants on a false pretext.

Answer

C