A nurse is collecting data from an infant. Which of the following is a clinical manifestation of pyloric stenosis?

A. Projectile vomiting after feedings: Projectile vomiting after feedings, especially occurring a short time after feeding, is a classic sign of pyloric stenosis due to obstruction at the pylorus. B. Absent bowel sounds: Absent bowel sounds may occur in more advanced cases of bowel obstruction but are not specific to pyloric stenosis. C. Increased sodium level: Increased sodium level is not typically associated with pyloric stenosis. D. Golf ball-size mass over the left quadrant: A palpable mass in the left quadrant is not a typical finding in pyloric stenosis.