The correct answer is B.
Every bill, order or resolution approved by the Congress of the United States has to be approved by the President. If the Presidents signs a particular bill, the bill becomes law. If he doesn't agree with a particular bill, he can use his presidential power of a veto.
A vetoed bill returns to Congress. Each house of the Congress may vote to override the veto. If 2/3 of each house agree to override the president's veto, the bill is enacted into law.
A senator who wants a bill he supports to become law, would seek the legislative tool of overriding the President's veto.