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
Bradykinin is a clevage product of - 
Select and explain. 
A. Kininogen, B. Prekallikrein, C. Kallikrien, D. Histamine
A: Kininogen
Answer: A: Kininogen 
Explanation: Ans. is 'a' i.e., Kininogen