Parents of a 6-month-old child, diagnosed with iron deficiency anemia, ask why it was not diagnosed earlier. What should the nurse say?

The correct answer is B: 'Maternal stores of iron are depleted at about 6 months.' Iron deficiency anemia becomes apparent around 6 months of age when the infant's iron stores, primarily received from the mother during pregnancy, are depleted. This timing coincides with the introduction of solid foods, which may lack sufficient iron. Choices A, C, and D are incorrect because they do not address the specific reason why iron deficiency anemia is typically diagnosed around 6 months of age.