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': "Which one of the following is the least likely cause of this patient's symptoms of retrobulbar swelling and diplopia? \nSelect and explain. \nA. Dermatomyositis, B. Cancer, C. Oral contraceptive use, D. Facial trauma", 'role': 'user'}, {'content': 'Answer: A \nExplanation: Answer A. DermatomyositisCerebral venous thrombosis can present with retrobulbar pain and vision changes. Risks for cerebral venous thrombosis include infections (sinus and ear), hypercoagulopathy, cancer, trauma, and the use of certain drugs. In this case, sinus infection can spread with direct extension or travel from mucosal veins to the venous sinuses.', 'role': 'assistant'}]