This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Ear, Subject name: ENT
[{'content': 'The size of the Fenestra vestibule on an average is \nSelect and explain. \nA. 3.50 mm long and 2.50 mm wide, B. 3.25 mm long and 1.75 mm wide, C. 3.75 mm long and 1.50 mm wide, D. 4.00 mm long and 2.00 mm wide', 'role': 'user'}, {'content': 'Answer: B \nExplanation: The size of the Fenestra vestibule on an average is 3.25 mm long and 1.75 mm wide. Ref- Dhingra ENT Textbook 6th edition.', 'role': 'assistant'}]