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: Ophthalmology
[{'content': 'The commonest type of cataract in adults is: \nSelect and explain. \nA. Nuclear cataract, B. Coical cataract, C. Morgagnian cataract, D. None of the above', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans. Coical cataract', 'role': 'assistant'}]