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: Physiology
Delay in blood coagulation results from 
Select and explain. 
A. Human thrombin, B. Heparin, C. Ferric chloride, D. Vit-K
B: Heparin
Answer: B: Heparin 
Explanation: None