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': 'True about cystic hygroma - \nSelect and explain. \nA. Congenital sequestration of lymphatics, B. Resolves spontaneouly by 5 year of age, C. Common in upper 1/3rd of lateral neck, D. All', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Answer is \'a\' i.e. Congenital sequestration of lymphatics "Bailey writes that spontaneous regression may occur in cystic hygroma but I am not sure whether it occurs by 5 yrs of age".', 'role': 'assistant'}]