Which of the following is a power of the U.S. Congress?

The power of the U.S. Congress primarily includes writing laws, which falls under its legislative authority. Congress is tasked with creating, amending, and repealing legislation that governs the nation. This is a fundamental role within the framework of the federal government, as established by the U.S. Constitution.

The separation of powers delineates distinct responsibilities among the three branches of government: the legislative, executive, and judicial branches. While Congress can draft and pass laws, the executive branch is responsible for enforcing those laws, and the judicial branch interprets them. Therefore, writing laws is an essential function of Congress, making it the correct answer in this context.