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
Common step in coagulation pathway is - 
Select and explain. 
A. Activation of factor VII, B. Activation of factor VIII, C. Activation of factor IX, D. Activation of factor X
D: Activation of factor X
Answer: D: Activation of factor X 
Explanation: Ans. is 'd' i.e., Activation of factor X o Blood coagulation pathways are divided into:-i) Intrinsic pathway (contact pathway) : It is largely an 'in vitro9 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.