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: Forensic Medicine
A mentally ill person smells unpleasant odor when none is present. This is an example of: COMEDK 07; KCET 13 
Select and explain. 
A. Illusion, B. Delusion, C. Obsession, D. Hallucination
D: Hallucination
Answer: D: Hallucination 
Explanation: Ans. Hallucination