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: Biochemistry
[{'content': 'CH2 transfer reaction is mediated by: \nSelect and explain. \nA. Folic acid, B. Butyric acid, C. Vit. 1312, D. None of the above', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Folic acid', 'role': 'assistant'}]