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': "Horner's syndrome is seen in all except \nSelect and explain. \nA. Carotid aery aneurysm, B. Medial medullary syndrome, C. Can occur following surgery for raynaud's Syndrome, D. Multiple sclerosis", 'role': 'user'}, {'content': "Answer: B \nExplanation: Horner syndrome, characterized by ptosis and miosis, is caused by compression of the ascending sympathetic supply within the carotid sheath and occurs in fewer than half of affected patients Extracranial dissection of the internal carotid aery causes cranial nerve palsy in 12% of cases It seems remarkable that multiple sclerosis does not commonly cause a Horner's syndrome for this syndrome is a manifestation of many different disease processes which affect the caudal brainstem and cervical spinal cord, as does multiple sclerosis Ref Harrison20th edition pg 2234", 'role': 'assistant'}]