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: ENT
[{'content': 'Normal volume of middle ear and mastoid ? \nSelect and explain. \nA. 1 cc, B. 6 cc, C. 12 cc, D. 15 cc', 'role': 'user'}, {'content': "Answer: B \nExplanation: Ans. is 'b' i.e., 6 cc l ReJ: Glasscock-shambaugh surgery of the ear p. 65)The normal average volume of middle ear and mastoid is 6 cc.", 'role': 'assistant'}]