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
[{'content': 'Clotting factor common to extrinsic and intrinsic pathway is: \nSelect and explain. \nA. Factor II, B. Factor III, C. Factor V, D. Factor VII', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Tissue factor initiates the extrinsic pathway, whereas contact of Factor XII and platelets with collagen in the vascular wall initiates the intrinsic pathway.\nAn especially important difference between the extrinsic\xa0 and\xa0 intrinsic\xa0 pathways is that the extrinsic\xa0 pathway can be explosive; once initiated, its speed of completion to the final clot is limited only by the amount of tissue factor released from the traumatized tissues and by the quantities of Factors X, VII,\xa0 and V in the blood. With severe tissue trauma, clotting can occur in as little as 15 seconds. The intrinsic pathway is much slower to proceed, usually requiring 1 to 6 minutes to cause clotting.\xa0\nClotting factor common to extrinsic and intrinsic pathway is Factor V.', 'role': 'assistant'}]