The correct answer is C. Vetoing.
The president has the power to veto any law passed by Congress. A veto is essentially a rejection/refusal to sign the law into place. This is one of the elements of the system of checks and balances that we have in the US government. However, the legislature can still pass this law by doing an override. This requires a 2/3rd majority vote in both the House of Representatives and the Senate.
