Idioms and Phrases - Verbal and Reasoning

In the following questions four alternatives are given for the idiom/phraseitalicised and underlinedin the sentence. Choose the alternative which best expresses the meaning of idiom/phrase.
Q1:

He is always standing up for the weak and oppressed.

A Boosting the claims of

B Championing the cause of

C Seeking help of others for

D Moving about with

ANS:B - Championing the cause of

No answer description is available.