The Joint Resolution below was passed by Congress on April 6, 1917. Therefore be it resolved by the Senate and the House of Representatives of the United States of America in Congress assembled, that the state of war between the United States and the Imperial German Government which has thus been thrust upon the United States is hereby formally declared; and that the President be, and he is hereby, authorized and directed to employ the entire naval and military forces of the United States and the resources of the Government to carry on war against the Imperial German Government.

​Which event led to this Joint Resolution?
A. the German invasion of Poland
B. the United States had a defensive alliance with Britain and France
C. submarine attacks on American ships
D. a terrorist attack on the World Trade Center and Pentagon