Correct, C is the correct answer.
Violation of the Munich Agreement - Six month after signing the Munich Agreement, Hitler violated the agreement and abolished Czechoslovakia.
Annexation of Austria - In 1938 German troops march into Austria for the Third Reich, earlier in that year the Nazi seize control over their government and unite with Germany.
Blitzkrieg into Poland - I'm pretty sure you know information about this but basically Germany invaded Poland that leads (I think) France and Britain to go to war with Germany.