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
Husband having suspicion that his wife is having affair with another man, diagnosis is ? 
Select and explain. 
A. Illusion, B. Delusion, C. Hallucination, D. Delirium
B: Delusion
Answer: B: Delusion 
Explanation: Ans. B. DelusionA delusion is false, firm (unshakeable) beliefthat is not accepted by other members of patient's culture and society.Above is an example of delusion of infedility (morbid jealousy, othello syndrome) i.e-. False belief that one's lover has been unfaithful.