The correct answer is A. The Department of Defense was created to place the US Army and Navy in one executive department.
The United States Department of Defense is a department of the executive branch of the federal government of the United States in charge of coordinating and supervising all government agencies and functions directly related to national security and the United States Armed Forces.
Following the aftermath of World War II, President Harry Truman proposed the creation of a unified department of national defense. In a special message to Congress on December 19, 1945, the President cited both inter-departmental conflicts and excessive spending on military matters. The deliberations in Congress lasted for months, focusing largely on the role of the military in society and the threat of giving too much military power to the executive branch.
