Final answer:
The charge nurse should delegate the task of assisting a client who had a hip arthroplasty to a chair to assistive personnel, as it's within their scope under the supervision of a registered nurse.
Step-by-step explanation:
The charge nurse is responsible for planning assignments and deciding which tasks to delegate to assistive personnel (AP). The appropriate task to delegate to an AP out of the options provided is assisting a client who had a hip arthroplasty to a chair. This is because APs are typically trained to help with the basic activities of daily living and mobility assistance under the direct supervision of a registered nurse. On the other hand, instructing a client on the use of a glucometer, interpreting vital signs, and cleansing the site of a midline catheter are tasks that require more advanced knowledge and skills that are within the scope of practice of a nurse or other licensed healthcare professional.