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: Biochemistry
[{'content': 'Negative nitrogen balance is the characteristic feature of which phase of convalescence after surgery? \nSelect and explain. \nA. Catabolic phase, B. Anabolic phase, C. Fat gain phase, D. Tuning point phase', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]