This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Neuro-ophthalmology, Subject name: Ophthalmology
[{'content': 'Hutchinson pupil is seen in which nerve palsy \nSelect and explain. \nA. Optic nerve, B. Occulomotor nerve, C. Abducent nerve, D. Trochlear nerve', 'role': 'user'}, {'content': "Answer: B \nExplanation: Caused by compression of the third nerve. Hutchinson pupil is dilation of pupil in one eye when the other eye is contracted Hutchinson's pupil is a clinical sign in which the pupil on the side of an intracranial mass lesion is dilated and unreactive to light, due to compression of the oculomotor nerve on that side. The sign is named after Sir Jonathan Hutchinson Reference: Aravind FAQS in Ophthalmology; First Edition; Page no: 491", 'role': 'assistant'}]