i think you should undertake this job; it would really be a profitable venture for you.

Answer: Option B

Undertake : commit oneself to and begin (an enterprise or responsibility); take on.
Refrain : stop oneself from doing something.
Leave : go away from.
Conceal : not allow to be seen; hide.
Retrieve : get or bring (something) back from somewhere.

Antonym of Undertake is Leave