Career in the Stock market

Which central agency is responsible for the regulation of the Stock Market in India ?

In the following questions, four alternatives are given for the idiom/ phrase printed in bold in the sentence. Choose the alternative which best expresses the meaning of the idiom/phrase as your answer. His investments helped him make a killing in the stock market.

Pattrick, a writer, wants to trade in stock market but have no knowledge of it. You area stock market advisor. Advice him about the working of Demat account, so that he could trade in securities.