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: Microbiology
[{'content': 'Hereditary angioneurotic edema is due to ? \nSelect and explain. \nA. Deficiency of C1 inhibitor, B. Deficiency of NADPH oxidase, C. Deficiency of MPO, D. Deficiency of properdin', 'role': 'user'}, {'content': "Answer: A \nExplanation: Ans. is 'a' i.e., Deficiency of C1 inhibitor Hereditary angioneurotic edema is due to C1inhibitor (Ci esterase inhibitor) deficiency.", 'role': 'assistant'}]