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
Following TPN, one expects weight gain after ? 
Select and explain. 
A. 2 days, B. 7 days, C. 4 weeks, D. 6 weeks
B: 7 days
Answer: B: 7 days 
Explanation: Ans. is `b' i.e., 7 days