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: Medicine
[{'content': 'Feature of hemorrhagic disease of new born is? \nSelect and explain. \nA. Prolonged prothrombin time, B. Defective platelet count, C. Prolonged bleeding time, D. Prolonged thrombin time', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Answer is A (Prolonged prothrombin time) Hemorrhagic disease of new born results from a deficiency of vitamin K. Prothrombin time is the single best laboratory test to detect vitamin K deficiency as vitamin k deficiency may present with isolated prolongation of PT Laboratory features of vitamin k deficiency (CMDT-2008) Both PT and PTT are prolonged but prolongation of PT is a more sensitive test to detect vitamin K deficiency than PTT - The PT is prolonged to a greater extent than PTT - With mild vitamin K deficiency only the PT is defective Fibrinogen level, Thrombin time and platlet count are not affected - CMDT', 'role': 'assistant'}]