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: Pediatrics
[{'content': 'A child with prolonged apTT underwent laprotomy and still did not develop any bleeding complications. Which of the following clotting factors is most likely to be deficient? \nSelect and explain. \nA. Factor VII, B. Factor X, C. Factor XII, D. Factor XIII', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Factor XII deficiency :\n\nAssociated with increased aPTT\nUsually asymptomatic\nResults in thrombosis rather than bleeding.', 'role': 'assistant'}]