What prompted the United States to join the fighting in World War I?
a. the assassination of an archduke
b. an attack on Pearl Harbor
c. the sinking of American ships in the Pacific
d. the sinking of American ships in the Atlantic
C. the sinking of ships in the pacific . The immediate cause of America's entry into World War I in April 1917 was the German announcement of unrestricted submarine warfare, and the subsequent sinking of ships with Americans on board
