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: Surgery
[{'content': 'Earliest tumor to appear after birth is \nSelect and explain. \nA. Cystic hygroma, B. Lymphoma, C. Branchial cyst, D. Sternomastoid tumor', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]