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': 'Immature senile cataract can be best differentiated from mature senile cataract by: \nSelect and explain. \nA. Iris shadow test, B. Oblique illumination examination, C. Visual acuity testing, D. Distant direct ophthalmoscopy', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Ans. Distant direct ophthalmoscopy', 'role': 'assistant'}]