Answer:
C- he took advantage of appeasement and the lack of control in the League of Nations.
Step-by-step explanation:
Whilst Britain, France, the USA and the rest of the Allies were wondering how to persuade Hitler to stop, they used the method of appeasement, which is basically giving in to everything Hitler wants for the country, on the basis that eventually he'll give up and stop wanting lots- this didn't work, and allowed him to build his army, occupy the Sudetenland, and more, all disobeying the terms of the Treaty of Versailles.
Hope this helps!