The answer is b, as Germany first remilitarised the Rhineland, which Britain and France simply allowed to happen. Then, in 1938, the Germans held the Anschluss, annexing all of Austria, despite it going against the Treaty of Versailles. After this, in 1939, Germany demanded the Sudetenland from Czechoslovakia, later invading them. Finally, the Germans invaded Poland, which finally caused Great Britain and Grance to intervene as they declared war on Germany.