A parent tells a nurse that her toddler drinks a quart of milk a day and has a poor appetite for solid foods. The nurse should explain that the toddler is at risk for which of the following disorders?

The correct answer is B: Iron deficiency anemia. Toddlers who consume excessive milk are at risk for iron deficiency anemia because milk is low in iron and can inhibit iron absorption. Iron is essential for the production of red blood cells. Rickets (choice A) is caused by a deficiency of vitamin D, obesity (choice C) is related to excessive calorie intake, and diabetes mellitus (choice D) is linked to high blood sugar levels. Iron deficiency anemia is the most likely disorder in this case due to the poor appetite for solid foods and excessive milk consumption.