Question

What aspect of romantic writing did realist writers disapprove of?

Answer 1

The realist art is based on the concrete and real things and places. Its characters are ordinary people with the everyday language used. Its only interest is to represent the recent or contemporary life and events.

Because of that, it has no approval for the romantic way of representing things, since it goes against its believes. Romantic writers are interest in history or legends, with a formal and inflated language, made up, exotic or mysterious settings and extravagant characters. Making so letter D correct, realist writers disapprove romantics for its "fanciful treatment of material".

Answer 2

Realist is a thought that judge the real things with perceptions and realism is opposite to idealism. 
therefore,
realist writers disapprove of the fanciful treatment of material.
hence the right option is D) the fanciful treatment of material