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': 'Circumference of an adult eyeball is: \nSelect and explain. \nA. 80 mm, B. 65 mm, C. 75 mm, D. 70 mm', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Ans. 75 mm', 'role': 'assistant'}]