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 60 year old male suffering from auditory hallucination says that people staying upwards are talking about him and conspiring against him. He dropped a police compliant against them but the allegations were proved to be wrong. The diagnosis is: 
Select and explain. 
A. Depression, B. Dementia, C. Delusional disorder, D. Schizophrenia
D: Schizophrenia
Answer: D: Schizophrenia 
Explanation: D i.e. Schizophrenia