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
The diagnostic feature that differentiates PTSD from other disorders that occur following a stressful incident is: 
Select and explain. 
A. Episodic occurrence of symptoms, B. Severe anxiety and autonomic arousal, C. Re-experiencing and avoidance of trauma, D. Nightmares about the event
C: Re-experiencing and avoidance of trauma
Answer: C: Re-experiencing and avoidance of trauma 
Explanation: Ans. c. Re-experiencing and avoidance of trauma