This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: C.V.S., Subject name: Pediatrics
[{'content': 'Iron stores are best indicated by: \nSelect and explain. \nA. S. ferritin, B. S. Iron, C. S. Transferrin, D. TIBC', 'role': 'user'}, {'content': "Answer: A \nExplanation: a. S. ferritin(Ref: Nelson's 20/e p 2323-2325, Ghai 8/e p 334-335)Serum ferritin reflects the storage of Iron which is decreased even in the pre-latent stage of Iron deficiency Anemia and is the most sensitive marker.", 'role': 'assistant'}]