Which of the following is a sign of severe dehydration in an infant?

Correct Answer: A

Rationale: A sunken fontanel is a classic sign of severe dehydration in infants, indicating significant fluid loss and the need for immediate hydration.

Correct Answer: C

Rationale: Renal tubular acidosis causes normal anion gap metabolic acidosis, not high anion gap metabolic acidosis.

Correct Answer: D

Rationale: Congenital anomalies are the leading cause of neonatal mortality in full-term newborns, as they often result in severe structural or functional abnormalities that are incompatible with life.

Correct Answer: D

Rationale: Kawasaki disease is diagnosed based on fever for ≥5 days and at least four of five criteria, including bilateral bulbar conjunctival injection without exudate.

Correct Answer: C

Rationale: Metabolic acidosis due to bicarbonate loss triggers respiratory compensation via hyperventilation (Kussmaul breathing) to reduce CO2 levels.