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: Medicine
[{'content': 'Which of the following is not a feature of cluster headache ? \nSelect and explain. \nA. Headache is predominantly unilateral, B. Affects predominantly females, C. Onset typically occur in 20-50 years of life, D. Associated with conjunctival congestion', 'role': 'user'}, {'content': "Answer: B \nExplanation: Cluster headache occur three times more common in men than in women. Cluster headache is likely a disorder involving central pacemaker neurons in the region of the posterior hypothalamus. It is associated with symptoms such as conjunctival injection or lacrimation, rhinorrhea or nasal congestion, or cranial sympathetic dysfunction such as ptosis. These defects occur due to parasympathetic activation which occur as a result of injury to ascending sympathetic fibers surrounding a dilated carotid aery as it passes into the cranial cavity. Ref: Harrison's Internal Medicine, 18th Edition, Chapter 14", 'role': 'assistant'}]