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': 'Middle ear cavity is formed by pharyngeal pouch \nSelect and explain. \nA. 1, B. 2, C. 3, D. 4', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Pouch Derivatives 1st Eustachian tube(opens into nasopharynx) and middle ear cavity 2nd Lines tonsillar crypts, forms endodermal epithelium of tonsil 3rd Dorsal - Inferior parathyroid glands Ventral - Thymus 5th fuses with 4th pouch Dorsal - Superior parathyroid glands Ventral - Ultimobranchial body recieves neural crest cells and changes to parafollicular c cells', 'role': 'assistant'}]