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': 'All of the following are mediators of acute inflammation except - \nSelect and explain. \nA. Angiotensin, B. Prostaglandin E2, C. Kallikrein, D. C 3a', 'role': 'user'}, {'content': 'Answer: A \nExplanation: . Angiotensin', 'role': 'assistant'}]