This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Misc., Subject name: Anatomy
[{'content': 'At 30 days intra uterine life \nSelect and explain. \nA. Heart starts beating, B. Cerebellum develops, C. Optical vesicle appears, D. Pinna appears', 'role': 'user'}, {'content': 'Answer: D \nExplanation: (D) Pinna appears # Development of External Ear:> Auricle, or pinna, is formed from about six mesodermal thickenings (called tubercles or hillocks) that appear on the Mandibular (First) & Hyoid (Second) arches, around the opening of the dorsal part of the first ectodermal cleft (i.e. around the opening of the external acoustic meatus).> External acoustic meatus is derived from the dorsal part of the first ectodermal cleft.> Mandibular arch forms only tragus & a small area around it, rest of the auricle being formed from the Hyoid arch.', 'role': 'assistant'}]