This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Sexual Disorders, Subject name: Psychiatry
A 16 year old girl who was sexually abused has no recollection for the event and is not able to remember anything despite her best effos. What is the diagnosis- 
Select and explain. 
A. Dementia, B. Dissociative amnesia, C. Factitious disorder, D. Malingering
B: Dissociative amnesia
Answer: B: Dissociative amnesia 
Explanation: Avoidance and 'dissociative' symptoms, such as difficulty in recalling the events at will, detachment, an inability to feel emotion ('numbness'), and a diminished interest in activities. There is avoidance of reminders of the events and sometimes there is depersonalization and derealization.