Correct Answer: B

Rationale: The sweat chloride test is the gold standard diagnostic test for cystic fibrosis as it measures the concentration of chloride in sweat. In cystic fibrosis, there is an abnormal transport of chloride across epithelial membranes, leading to elevated sweat chloride levels. A chest X-ray may show characteristic changes in the lungs associated with cystic fibrosis, but it is not a definitive diagnostic test. Pulmonary function tests assess lung function but do not specifically diagnose cystic fibrosis. Sputum culture may identify respiratory infections but does not confirm the diagnosis of cystic fibrosis.

Correct Answer: B

Rationale: The correct answer is B: Covering the sac with saline-soaked nonadhesive gauze. This intervention is essential in caring for an infant with myelomeningocele as it helps prevent infection and maintains a moist environment around the sac before surgical repair. Positioning the infant supine with a pillow under the buttocks (Choice A) may be suitable for comfort but is not directly related to managing the myelomeningocele. Wrapping the infant snugly in a blanket (Choice C) and applying a diaper (Choice D) are not recommended as they can increase the risk of infection and damage to the sac.

Correct Answer: B

Rationale: The correct first action before administering tube feeding to an infant is to offer a pacifier. Providing a pacifier stimulates the sucking reflex, aiding in digestion and providing comfort to the infant. Irrigating the tube with water (Choice A) is not typically the initial step and could potentially introduce unnecessary fluid into the infant's system. Slowly instilling formula (Choice C) should only be done after ensuring the tube is appropriately placed. Placing the infant in the Trendelenburg position (Choice D) is not necessary for tube feeding and could pose risks such as aspiration.

Correct Answer: B

Rationale: The correct answer is B: Diarrhea. Rotavirus infection commonly presents with symptoms such as watery diarrhea, vomiting, fever, and abdominal pain. While abdominal pain and vomiting are also associated with rotavirus infection, diarrhea is a hallmark feature. Constipation is not typically seen in cases of rotavirus infection. Therefore, the most likely clinical manifestation that the nurse would observe in a child with suspected rotavirus infection is diarrhea.

Correct Answer: B

Rationale: The correct answer is B: Diarrhea. Rotavirus infection commonly presents with symptoms such as watery diarrhea, fever, vomiting, and abdominal pain. However, diarrhea is the hallmark symptom of rotavirus infection, often leading to dehydration in children. Abdominal pain (choice A) can also be present but is not as specific to rotavirus infection as diarrhea. Constipation (choice C) is not a typical symptom of rotavirus infection. While vomiting (choice D) can occur in rotavirus infection, it is more commonly associated with other gastrointestinal conditions.