This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Blood, Subject name: Pediatrics
[{'content': 'An otherwise healthy child has on his 1-year-old routine CBC the polymorphonuclear neutrophil shown below. Which of the following is an appropriate next step? \nSelect and explain. \nA. Bone marrow aspiration, B. Begin oral iron therapy, C. Begin folic acid supplementation, D. Hemoglobin electrophoresis', 'role': 'user'}, {'content': 'Answer: C \nExplanation: The finding of hyper-segmented neutrophils in the peripheral blood is one of the most useful laboratory aids in making an early diagnosis of folate deficiency. Serum folate levels become low in weeks with an inadequate dietary source.', 'role': 'assistant'}]