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 cause of cataract – \nSelect and explain. \nA. Hereditary, B. DM, C. Trauma, D. Age related', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Most common type of cataract is senile (age-related) cataract.', 'role': 'assistant'}]