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': "All are false about McEwen's triangle except: \nSelect and explain. \nA. Mastoid antrum lies 1.5 cm deep to it, B. Surgical landmark for facial nerve, C. Present in preauricular region, D. It is bounded by suprameatal crest anteriorly", 'role': 'user'}, {'content': 'Answer: A \nExplanation: (a) Mastoid antrum lies 1.5cm deep to it(Ref. Shambaugh, 6th ed., page 32)It is a surgical landmark for the mastoid antrum, lying in the postauricular area. It is bounded superiorly by temporal line/supra mastoid crest which is the posterior extension of suprameatal crest.The suprameatal crest is the superior root of the zygomatic process.', 'role': 'assistant'}]