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
Flashback is characteristic of : 
Select and explain. 
A. Hypomania, B. Post traumatic stress disorder, C. Postnatal depression, D. Grief reaction
B: Post traumatic stress disorder
Answer: B: Post traumatic stress disorder 
Explanation: Recollection of the stressful event in images / thought / perceptions (i.e. flash back) is seen in PTSD.