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
[{'content': 'All are predisposing causes of cerebral venous thrombosis except \nSelect and explain. \nA. Hypotension, B. Oral contraceptives, C. Pregnancy, D. Aplastic anaemia', 'role': 'user'}, {'content': "Answer: D \nExplanation: *predisposing systemic causes for cerebral venous thrombosis: dehyration,pregnancy,Behcet's disease ,thrombophilia,hypotension,oral contraceptive use. *Local causes are:paranasal sinusitis,meningitis,subdural empyema,facial skin infection,otitis media,mastoiditis,skull fracture,penetrating head and eye wounds. Ref Harrison20th edition pg 2345", 'role': 'assistant'}]