Please HELP!

"Around the beleaguered Four Courts the heavy guns roared. Here and there through the city, machine guns and rifles broke the silence of the night, spasmodically, like dogs barking on lone farms. Republicans and Free Staters were waging civil war."

The literary element BEST illustrated in this passage from "The Sniper" is

A. theme.
B. conflict.
C. irony.
D. setting.