Why Did Socialist Parties Become More Moderate by the Late

Why did socialist parties become more moderate by the late 1800s?

A) Socialist leaders saw revolution as a threat to their increasingly respectable social positions.
B) The increasingly radical and aggressive trade union movements frightened socialist parties and turned them in a more moderate direction.
C) Socialist leaders, like so many of their followers, became ardent patriots and grew as nationalistic as conservatives.
D) As socialist parties attracted larger numbers of members, they looked more toward gradual change and less toward revolution.