This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: ENT
[{'content': 'Commonest site of nasopharyngeal carcinoma is: \nSelect and explain. \nA. Roof, B. Posterior, C. Lateral wall, D. Anterior wall', 'role': 'user'}, {'content': 'Answer: C \nExplanation: The lateral walls include the eustachian tube, the torus tubarius, and the fossa of Rosenmuller. The most common site of origin for nasopharyngeal carcinoma is the fossa of Rosenmuller.', 'role': 'assistant'}]