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': 'Pitting edema indicates an excess of .... litres of fluid in tissue spaces - \nSelect and explain. \nA. 2.5, B. 3.5, C. 4.5, D. 5.5', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]