This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Blood: Hemostasis and Blood Coagulation, Subject name: Physiology
Major in vivo pathway of coagulation - 
Select and explain. 
A. Contact pathway, B. Intrinsic pathway, C. Extrinsic pathway, D. None of the above
C: Extrinsic pathway
Answer: C: Extrinsic pathway 
Explanation: Ans. is 'c' i.e., Extrinsic pathwayo Blood coagulation pathways are divided into :-i) Intrinsic pathway (contact pathway): It is largely an 'in vitro' pathway and is activated when factor XII (Hageman factor or contact factor) comes in contact with negatively charged surface, e.g. glass, kaolin etc.ii) Extrinsic pathway: It is largely an in vivo pathway is activated by tissue factor (thromboplastin) at the site of tissue injury.