Which pair of pediatric clients can be safely assigned to a semi-private room?

The correct answer features a scenario where both pediatric clients can be safely accommodated in a semi-private room due to their medical conditions not posing any risk of spreading infection to one another. The 4-year-old girl in Buck traction is being treated for a musculoskeletal issue that does not involve an infectious process, while the 5-year-old boy who is post laparoscopic appendectomy is recovering from a surgical procedure that typically does not involve any contagious conditions.

In a semi-private setting, it is crucial that the patients do not suffer from conditions that could potentially transmit infectious diseases. This is why other pairings, such as the options involving varicella and measles, rotavirus and salmonella, or sickle cell anemia and periorbital cellulitis, would not be appropriate. Both varicella and measles are highly contagious conditions, and having those clients in the same room poses a significant risk to their safety. Similarly, the rotavirus and salmonella infections are also infectious, making it unsafe to have those patients share a room. Thus, option A stands out as the only combination of patients that ensures safety and minimizes infection risk.