This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Bleeding Disorders, Subject name: Pathology
[{'content': 'Which coagulation factor is not in circulating form in blood? \nSelect and explain. \nA. F XI, B. F X, C. F III, D. F XIII', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Ans. (c) F IIITissue factor (factor III) is also called as platelet tissue factor. It is found on the outside of blood vessels and is not exposed to the bloodstream. It initiates the extrinsic pathway at the site of injury.', 'role': 'assistant'}]