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': 'Following TPN, one expects weight gain after - \nSelect and explain. \nA. 2 days, B. 7 days, C. 4 weeks, D. 6 weeks', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]