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': 'Grade I lymphedema means - \nSelect and explain. \nA. Pitting edema upto the ankle, B. Pitting edema upto the knee, C. Non-pitting edema, D. Edema disappearing after overnight rest', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]