The primary function of the judicial branch is to interpret laws. This involves determining their meaning and application, ensuring justice is served according to the law.

The executive branch has the power to veto legislation, which allows the President to reject bills passed by Congress. Declaring war is a power of Congress, interpreting laws is a judicial power, and impeaching officials is a legislative function.

The main role of the legislative branch is to make laws. This branch, which includes Congress, is responsible for drafting, debating, and passing legislation that governs the country.

The Supreme Court is the highest court in the United States judicial branch, having the ultimate authority in interpreting the Constitution and federal law, unlike the Court of Appeals, District Court, or Family Court.

The head of the executive branch at the federal level is the President. This role includes enforcing laws, directing the government, and serving as the Commander-in-Chief of the armed forces.

The United States Congress is made up of two houses: the Senate and the House of Representatives. Therefore, the correct answer is 'Two'.

Judicial review is the power of courts to evaluate laws and declare them unconstitutional if they violate the Constitution. This process ensures that legislative actions align with constitutional principles.