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': 'Persistent belief in something which is not a fact is - \nSelect and explain. \nA. Illusion, B. Hallucination, C. Delusion, D. Delirium', 'role': 'user'}, {'content': "Answer: C \nExplanation: A delusion is false, firm (unshakable) belief which are not in keeping with patient's socio-cultural and educational background.", 'role': 'assistant'}]