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 patient presents with a history of continuous headache for the past 8 years. Repeated examinations had failed to reveal any lesion. The patient is convinced that he has a tumor in his brain. The diagnosis is: NIMHANS 08 
Select and explain. 
A. Hypochondriasis, B. Somatization, C. Somatoform pain disorder, D. Obsessive Compulsive Disorder
A: Hypochondriasis
Answer: A: Hypochondriasis 
Explanation: Ans. Hypochondriasis