Final answer:
The nurse should clean the open area with mild soap, dry it, and apply a light dressing.
Step-by-step explanation:
The nurse should implement action d. Clean with mild soap, dry, and apply a light dressing for the open area on the sacrum that appears blistered. Cleaning the area with mild soap can help remove any debris or bacteria, and drying it helps to prevent further moisture buildup. Applying a light dressing can provide protection to the wound and promote healing.