What did the department of war do

The War Department was the United Kingdom government department responsible for the supply of equipment to the armed forces of the United Kingdom and the pursuance of military activity.

The United States Department of War, also called the War Department (and occasionally War Office in the early years), was the United States Cabinet department originally responsible for the operation and maintenance of the United States Army.

answer; /// i do believe that the correct answer is (d) cooperative play; /// good luck

can you explain it better