During a 24-hour period an otherwise healthy 5-month-old (weighing 12 pounds) has had several episodes of diarrhea and low-grade fever. The caregiver asks whether to start offering plain water in addition to breast milk or formula. What is the best evidence-based recommendation?

• A. Dilute infant formula 1:1 with water to increase fluid intake while decreasing nutrient density, which is the standard first-line approach
• B. Offer undiluted fruit juice to replace electrolytes quickly and provide simple sugars for energy during illness
• C. Immediately stop breast milk/formula and give only plain water to flush out pathogens and rapidly rehydrate the infant at home
• D. Continue frequent breast milk or formula feeds because they provide fluid and electrolytes; consult pediatrician if dehydration signs appear—only offer small amounts of oral rehydration solution or water if recommended by a clinician

Answer: (D)