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': 'Exudate in rheumatic fever is - \nSelect and explain. \nA. Serous, B. Purulent, C. Fibrinous, D. Myxomatous', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]