The nations of Europe did not stop Germany from re-militarizing the Rhineland or annexing Austria and the Sudetenland because: the League of Nations was not effective. All of the choices are correct. Great Britain and France feared another war. the citizens of those regions were primarily German speakers.

All of the choices are correct, except maybe the German speakers part. The League of Nations did not work well, because only a couple powerful nations were a part of it, and the US was not one (Despite it being Wilson's idea, Congress realized American Progressive ideals did not work in Europe, and so backed out of the LoN). Great Britian and France tried an "appeasement" policy with Germany in order to try and "fill" Hitler's appetite for land. They may have done this because those areas had German Speakers because they were taken from Germany in WWI as part of the restrictions placed on Germany in the Treaty of Versailies. If it isn't all the choices, it is GB and France feared another war, but I bet all of the choices are correct.