Which of these was most responsible for the beginning of european recovery after world war ii?

Are there any answer options that I can see?

The league of nations was found in 1919 to keep peace after world war l.but it failed to prevent world war ll in 1939,so in 1945 the nations of the world set up a new organization,the united state (un).since then, the un has encouraged international cooperation and worked to resolve conflict

The answer is option e.