In the 1930s, Italy and Germany resorted to acts of aggression similar to those of Japan in Asia. Throughout the decade, neither the League of Nations nor democratic nations succeeded in stopping the aggression. Which action by Adolf Hitler demonstrated the weakness of the League of Nations?

A.
Hitler's effort to rebuild the German economy

B.
Hitler's attempt to enlarge the German army, navy, and air force

C.
Hitler's decision to send troops into the Rhineland

D.
Hitler's speech on the need for Germany to expand