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: Medicine
A nine month old boy of Sindhi parents presented to you with complaints of pregressive lethargy, irritability & pallor since 6 months of age. Examination revealed severe pallor. Investigation showed Hb-3.8 mg%; MCV-58 fl; MCH-19.4 pg/ cell. Blood film shows osmotic fragility is normal (target cells and normoblasts). X-ray skull shows expansion of erythroid marrow. Which of the following is the most likely diagnosis - 
Select and explain. 
A. Iron deficiency anemia, B. Acute lymphoblastic anemia, C. Hemoglobin D disease, D. Hereditary spherocytosis
A: Iron deficiency anemia
Answer: A: Iron deficiency anemia 
Explanation: None