Final answer:
A 4-week-old infant with pyloric stenosis is expected to have symptoms of frequent projectile vomiting, which is what a nurse would expect the parent to report.
Step-by-step explanation:
A 4-week-old infant with symptoms of pyloric stenosis typically presents with projectile vomiting after feeding. Therefore, the statement that a nurse would expect the parent to make about the infant’s symptoms is: "My baby has been having frequent, projectile vomiting." Pyloric stenosis is a condition where the pylorus muscles are hypertrophied, impeding the passage of food from the stomach into the duodenum, which leads to forceful vomiting, dehydration, and weight loss in young infants.