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': 'Crus commune is a part of: \nSelect and explain. \nA. Cochlea, B. Middle ear, C. Semicircular canal, D. Vestibule', 'role': 'user'}, {'content': 'Answer: C \nExplanation: (c) Semicircular canal(Ref Shambaugh, 6th ed., page 42)The posterior and superior semicircular canals fuse together to form a common crus called as "crus commune" which opens into the utricle. Because of this the three semicircular canals open into utricle by five openings instead of six.', 'role': 'assistant'}]