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: Pathology
[{'content': 'Normal amount of pleural fluid is approximately \nSelect and explain. \nA. 5ml, B. 15 ml, C. 50 mL, D. 100m1', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Normally, no more than 15 ml of serous, relatively acellular, clear fluid lubricates the pleural surface.\nIncreased accumulation of pleural fluid is called pleural effusion', 'role': 'assistant'}]