PLEASE HELP I'M DOING A UNIT TEST AND I NEED TO GET THIS RIGHT!!! Please and Thank you!!

Why did the United States enter World War 2??

A.) To put an end to Japanese brutality against the Chinese people

B.) To prevent Hitler from conquering the Soviet Union and murdering Europe's Jews

C.) Because Churchill convinced Roosevelt that Britain was about to fall to the Nazis

D.) Because Japan launched an air attack against the U.S. Pacific fleet in Hawaii