What was the main cause of World War II?
1.Franklin Roosevelt was elected president in 1940.
2.The United States sold goods to its allies in Europe.
3.The United States declared war on Germany and Italy.
4.Germany began to expand its territory through conquest.
4. Germany began to expand its territory through conquest.
The main cause of World War II was the aggressive actions of Germany, led by Adolf Hitler, who sought to expand its territory and establish a new order in Europe. Hitler's invasions of Poland, Czechoslovakia, and other countries ultimately led to the outbreak of the war in 1939.