A 6-month-old infant diagnosed with gastroesophageal reflux disease (GERD) presents with poor weight gain, frequent regurgitation, and occasional respiratory distress. The nurse must prioritize interventions to manage GERD effectively. Which nursing action is most appropriate to include in the care plan?

A. Infant can hold head steady before rolling over is correct because cephalocaudal growth and development occur from head to toe. Control of the head and neck muscles develops first, followed by control of the trunk and then the lower extremities. Being able to hold the head steady is an early milestone that clearly demonstrates cephalocaudal progression.

B. Infant can pick up small objects with thumb and forefinger is incorrect because this describes development of the pincer grasp, which reflects fine motor development and typically occurs later (around 9–12 months). It does not specifically demonstrate cephalocaudal progression.

C. Infant can sit independently is incorrect because sitting requires trunk and core muscle control, which develops after head control. While related to cephalocaudal development, it is not the best example because it occurs later in the sequence.

D. Infant can crawl using arms and legs simultaneously is incorrect because crawling involves coordinated use of both upper and lower extremities, which occurs later in infancy and reflects overall motor coordination rather than early head-to-toe development.

A. Sweat chloride test is correct because it is the gold standard diagnostic test for cystic fibrosis. In CF, mutations in the CFTR gene lead to abnormal chloride transport in epithelial cells. This results in elevated chloride levels in sweat, typically ≥60 mmol/L in children, which confirms the diagnosis.

B. Genetic testing for CFTR mutations is incorrect as the sole diagnostic tool because not all CF mutations are detectable, and testing may identify carriers or atypical variants. While genetic testing is useful for confirmation or family counseling, it is not the first-line diagnostic test.

C. Chest x-ray is incorrect because, although it may reveal hyperinflation, bronchiectasis, or infiltrates indicative of chronic lung disease in CF, it cannot confirm the diagnosis. Imaging is supportive but not diagnostic.

D. Pulmonary function tests (PFTs) are incorrect because these tests assess lung function and airflow limitation, but they are not diagnostic for CF, especially in young children who may not be able to perform the tests reliably.