Fascism is a political ideology that became popular in certain countries following world war i and was a response to fear of

I think the answer you're looking for is communism.
Fascism was however a result of many fears, some of them were the fear of certain minorities taking over the main part of economies (in Germany people believed that Jews were too powerful), and the fear of poverty, as people were thinking that only a strong government can provide for its people.

But in many places communism was used as a direct demagogic threat to gain support.

Where's the excerpt? also i think the answer is the last one