Explanation:

Correct Answer is (b).The given sentence has the type 3 conditional clause attached to it which can be framed in one of the two following ways:
Had I been a king ....
If I had been a king ...
The correct sentence will therefore be:
Had I been a king, I would have tried to do many things for the underprivileged section of the society.”This makes Option B the right choice among the given options.