Which entity has the power to approve or deny proposed legislation?

The U.S. Congress has the authority to approve or deny proposed legislation, making it the correct choice for this question. Congress is composed of two chambers: the House of Representatives and the Senate. When a bill is introduced, it must go through a series of steps, including committee reviews and votes in both chambers. Only if both the House and Senate approve the bill does it move forward to the President for consideration.

This process ensures that legislation is thoroughly evaluated and debated, representing the interests of the American people through their elected representatives. The roles of the President and the Supreme Court differ significantly; the President can veto legislation but does not have the power to approve it outright, while the Supreme Court's role is to interpret the law rather than to create or approve it. State legislatures have power over state laws but do not impact federal legislation in the same way that Congress does.