Please Help!

The diagram below shows groups that the Ku Klux Klan blamed for problems in the United States during the 1920s and 1930s:

Which statement explains why "Catholics and Jews" would complete the diagram above (technically below)?

1) Catholics or Jews led most organizations that opposed the Klan.

2) Most Communists and Bolsheviks were either Catholic or Jewish.

3) Catholics and Jews made up the majority of the U.S. population in the 1920s.

4) Most Klan members were Protestants who felt that other religions were inferior. (I don't think it's 4)