A toddler has had recurrent respiratory infections. The mother of the child expressed concern that her child seemed to be at increased risk for complications from infection in comparison with her older children. What is the best response from the nurse?

Rationale: A. "Air passages are more likely to become blocked with mucus because younger children make more mucus than do older children": Younger children are not constantly producing more mucus than older children. The increased risk is more related to anatomical and physiological differences rather than baseline mucus volume. B. "Airways structures are closer together so infection spreads faster in the young child": In toddlers, airway structures are smaller and in closer proximity, allowing pathogens to quickly move from one area to another. This proximity, combined with immature immune defenses, increases the likelihood of widespread infection and associated complications. C. "Younger children have more exposure to respiratory illnesses": While young children may be exposed frequently in settings like daycare, exposure alone does not explain increased severity or complications. The higher risk is due to their developing respiratory anatomy and immune system. D. "Toddlers do not breathe as deeply as do older children": Tidal volume in toddlers is smaller due to their smaller lung size, but this factor alone does not significantly explain their increased risk of complications from infection.