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': 'Umbilical cord has – \nSelect and explain. \nA. 1 vein and 2 arteries, B. 2 vein and 2 arteries, C. 1 vein and 1 artery, D. 2 veins and 1 artery', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]