This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Cognitive development and defence mechanism, Subject name: Psychiatry
[{'content': 'Defence mechanism in OCD \nSelect and explain. \nA. Progression, B. Regression, C. Magical thinking, D. Reaction formation', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Three defense mechanisms are common in OCD- Isolation, Undoing & Reaction formation Isolation: Unconsciously isolate and disown their own thoughts, experiencing as forign thoughts. Undoing: unconsciously cancel out an unacceptable desire or act by performing another act. Reaction formation: suppress an unacceptable desire by taking on a lifestyle that expresses the opposite desire.', 'role': 'assistant'}]