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': 'Flashback is characteristic of : \nSelect and explain. \nA. Hypomania, B. Post traumatic stress disorder, C. Postnatal depression, D. Grief reaction', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Recollection of the stressful event in images / thought / perceptions (i.e. flash back) is seen in PTSD.', 'role': 'assistant'}]