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 since 2 months suspects that his wife is having an affair with his boss. He thinks his friend is also involved from abroad and is providing technical support. He thinks people talk ill about him. His friends tried to convince him but he is not convinced at all. Otherwise, he is normal, he doesn't have any thought disorder or any other inappropriate behavior. The most likely diagnosis is - 
Select and explain. 
A. Paranoid personality disorder, B. Persistent delusion disorder, C. Schizophrenia, D. Acute and transient psychosis
B: Persistent delusion disorder
Answer: B: Persistent delusion disorder 
Explanation: Persistent delusional disorder is characterized by non bizarre delusions (i.e. involving situations that occur in real life e.g. deceived by spouse) of at least 1 month duration (DSM IV) but with absence of :

Prominent hallucinations & flattening of affect
Thought disorder, mood disorder, inappropriate behavior
Cognition, memory & consciousness impairment