C). The aftereffects of combat on soldiers during war.
Explanation:
The central idea discussed in both the works, Tim O'Brien's "Ambush" and John Steinbeck's "Symptoms" demonstrates 'the aftermath of combat on soldiers during the war'. 'Ambush' by Tim elaborates the story twenty years after the war being concluded where the speaker's daughter interrogates him if he had killed anyone and he lies to her that fills him with an intense guilt that has already been haunting him for years. While 'Symptoms' by Steinbeck too reinforces the loneliness and aftermath faced by the soldiers post-war . Thus, <u>option C</u> is the correct answer.
