Which of the following is not a branch of the U.S. military?

The correct answer is based on the fact that the U.S. military is comprised of several distinct branches, which include the Army, Navy, Air Force, Marine Corps, and Coast Guard. Each branch has its specific roles and responsibilities within the defense structure of the United States. The term "Maritime Force" does not refer to any officially recognized branch of the U.S. military. While the Navy conducts maritime operations, it is not designated as the "Maritime Force." Instead, the Navy is the branch responsible for naval operations. The Army is the ground warfare service, the Air Force handles aerial operations, and the Space Force focuses on operations in space. Thus, "Maritime Force" does not fit into the established structure of the U.S. military forces, making it the correct choice for this question.