This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Pharyngeal Arches, Subject name: Anatomy
[{'content': 'External auditory meatus is derived from which cleft? \nSelect and explain. \nA. 1, B. 2, C. 3, D. 4', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Cleft 1 forms external auditory meatus- surface ectoderm If the pharyngeal clefts are not obliterated by the 2nd pharyngeal arch, they can persist into adulthood as branchial (pharyngeal) cysts.', 'role': 'assistant'}]