This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Nutritional anemia, Subject name: Pediatrics
[{'content': 'First change of improvement noted after iron therapy is initiated: \nSelect and explain. \nA. Decreased irritability, B. Reticulocytosis, C. Increase in serum iron levels, D. Replenishment of iron stores', 'role': 'user'}, {'content': 'Answer: A \nExplanation: RESPONSE TO TREATMENT IN IRON DEFICIENCY ANEMIA: Time after Iron administration Response 12-24 hours Decreased irritability, increased appetite 48-72 hours Reticulocytosis, peaks at 5-7 days post treatment 4-30 days Increase in Hb level (best measure) 1-3 months Repletion of stores', 'role': 'assistant'}]