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': "Snellen's test types are based on the fact that two distant points can be visible as separate only when they subtend at the nodal point of the eye an angle of: \nSelect and explain. \nA. 1 minute, B. 3 minute, C. 5 minute, D. 2 minute", 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans. 1 minute', 'role': 'assistant'}]