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': 'Which of the following is not a derivative of the middle ear cleft? \nSelect and explain. \nA. Semicircular canal, B. Mastoid air cell, C. Tympanic cavity, D. Eustachian tube', 'role': 'user'}, {'content': 'Answer: A \nExplanation: The middle-ear cleft in the temporal bone includesEustachian tubeThe middle ear (tympanic cavity)Aditus which leads posteriorly to the mastoid antrum and air cellsRef: PL Dhingra, Diseases of Ear, Nose & Throat, 7th edition, pg no. 5', 'role': 'assistant'}]