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': 'Thyroid Opthalmopathy \nSelect and explain. \nA. Myasthenia Gravis, B. Marfan syndrome, C. Thyroid Opthalmopathy, D. Pancoast tumor', 'role': 'user'}, {'content': 'Answer: C \nExplanation: The question is on unilateral ptosis whereas thyroid opthalmopathy has PROPTOSIS. \n\nIn myasthenia gravis, due to anti-Ach-receptor blocking antibodies there is ptosis which can be unilateral or asymmetrical which will again appear unilateral.\nMarfan syndrome has congenital Ptosis.\nPancoast tumor causes horner syndrome in which unilateral sympathetic chain is compressed leading to Ptosis, Miosis, Anhidrosis, Enopthalmos and loss of Cilio-spinal reflex.', 'role': 'assistant'}]