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': 'In a normal adult person the depth of anterior chamber in the centre is about: \nSelect and explain. \nA. 2.5 mm, B. 3 mm, C. 3.5 mm, D. 4 mm', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans. 2.5 mm', 'role': 'assistant'}]