What is the most effective response to aggression-appeasement or a collective security?

Its collective security because great Britain (Neville chamberlain -GB prime minister) supported appeasement as the answer for the Czechoslovakia problem and then they allowed Hitler to take the Sudetenland...Hitler promised to recognize Czechs new boundary lines but six months later he took over all of Czech 
the french and British also supported the idea of appeasement when hitler wanted to take the Rhineland...which he later did. hitler himself later admitted that if the french and great Britain had tried to stop him he probably would have backed down 
like winston churchill said if the france and GB had decided to support czech with their problem ,big things could have been avoided 
basically find examples why appeasement was bad and then nsay instead collective security was a better idea! 
hope this helps

Soory i don’t know hope you get a good grade