Question

What aspect of fiction did realist writers use to advance the plot of their story?

Answer 1

next time please post the choices
A. The effect of destiny
B. Social trials
C. Tragic events
D. Complexity of character
that being said, we can eliminate the first two (realistic fiction doesn't typically emphasize the idea of "destiny," rather, it lets the events of the story/decisions of the characters/etc. drive the plot to its conclusion rather than some pre-destined ending)
social trials is also an odd choice, I tried googling and I couldn't really find a universal definition for what this actually is, my best guess is that it's a conflict arising from social issues/society which is not something universally present in realistic fiction

so going to the last two, personally I feel like both could work but complex characters is a better solution because not all realistic fiction involves grand, tragic events (some are more slice of lifey) whereas realistic fiction *is* more character-driven. in fiction it's common to have the focus be on a grand, external conflict and less focus on the characters, but the reverse situation for realistic fiction