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
A 30 year old man has become suspicious that his wife is having an affair with his boss. He thinks his friend is also involved from abroad by providing support his friends tried to convince him but failed to do so. The patient is otherwise normal, doesn't have any hallucination or any other socially inappropriate behavior. The most likely diagnosis is 
Select and explain. 
A. Schizophrenia, B. Acute Psychosis, C. Persistent delusional disorder, D. Adjustment disorder.
C: Persistent delusional disorder
Answer: C: Persistent delusional disorder 
Explanation: Patient is having paranoid delusion, and absence of hallucination, socially inappropriate behavior rules out psychosis. The most likely diagnosis is Presistent Delusional Disorder.