This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Psychiatry
[{'content': 'The diagnostic feature that differentiates PTSD from other disorders that occur following a stressful incident is: \nSelect and explain. \nA. Episodic occurrence of symptoms, B. Severe anxiety and autonomic arousal, C. Re-experiencing and avoidance of trauma, D. Nightmares about the event', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Ans. c. Re-experiencing and avoidance of trauma', 'role': 'assistant'}]