This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: C.N.S, Subject name: Medicine
Most common cause of headache- 
Select and explain. 
A. Tension headache, B. Migraine, C. Cluster headache, D. Trigemmal neuralgia
A: Tension headache
Answer: A: Tension headache 
Explanation: *Common cause of primary headache is tension headache(69%). *Migraine(16%)and cluster headache(0.1%) Ref Harrison20th edition pg 1234