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: Unknown
[{'content': 'The primitive gut is a derivative of - \nSelect and explain. \nA. Yolk sac, B. Amniotic cavity, C. Allantoic cavity, D. Coelum', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans: A', 'role': 'assistant'}]