This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: All India exam, Subject name: Physiology
[{'content': "Horner's syndrome is characterized by the following except \nSelect and explain. \nA. Ptosis, B. Miosis, C. Heterochromia iridis, D. Apparent exophthalmos", 'role': 'user'}, {'content': "Answer: B \nExplanation: Common signs and symptoms include: A persistently small pupil (miosis) A notable difference in pupil size between the two eyes (anisocoria) Little or delayed opening (dilation) of the affected pupil in dim light. Drooping of the upper eyelid (ptosis) Slight elevation of the lower lid, sometimes called upside-down ptosis Ref ganong's review of medical physiology 25e p431", 'role': 'assistant'}]