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': 'Which is not an ego defence mechanism : \nSelect and explain. \nA. Rationalization, B. Repression, C. Identification, D. Obsession', 'role': 'user'}, {'content': 'Answer: D \nExplanation: D i.e Obsession', 'role': 'assistant'}]