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: Surgery
[{'content': 'Sentinel lymphnode is: \nSelect and explain. \nA. Group of lymphnodes, B. First stop along the route of lymphatics, C. A node that is skipped during distant metastasis, D. Distant metastatic node', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]