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: Anatomy
[{'content': 'The lymphatic drainage of pyriform fossa is to: \nSelect and explain. \nA. upper deep cervical nodes, B. Prelaryngeal node, C. Para pharyngeal nodes, D. Mediastinal nodes', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Pyriform sinus drains into jugular chain and then to deep cervical group of lymph nodes. Post cricoid region drains into para pharyngeal and paratracheal group of lymph nodes. Posterior pharyngeal wall drains into para pharyngeal lymph nodes and finally to deep cervical lymph nodes. Ref Tuli 1/e,p 231,232.', 'role': 'assistant'}]