The correct answer is override a presidential veto.
In the US government, Congress is responsible for making national laws. After the bill has passed both houses of Congress (aka the House of Representatives and the Senate), the bill is then sent to the president to sign. However, the president can stop this bill from becoming law. This is known as a veto. If a president vetoes a law, it can still be passed without their signature. This requires a 2/3rd majority vote in both parts of Congress. If this happens, the bill becomes law.