Explanation:

The most appropriate assignment for a nursing assistant is to take the vital signs of a stable patient. A 10-year-old with a 2-day postappendectomy is considered stable, and routine vital signs monitoring can be safely delegated to a nursing assistant. Clients with bronchiolitis, periorbital cellulitis, and a fractured tibia require more specialized care and assessment by a licensed nurse. Bronchiolitis involves an airway alteration, periorbital cellulitis indicates an infection, and a fractured tibia may raise concerns of abuse. Therefore, options A, C, and D are incorrect for delegation to a nursing assistant.