Final answer:
Protein aids in the formation of new tissues during healing.
Step-by-step explanation:
The best response by the nurse regarding why the client is receiving protein supplements while healing from a bed sore is: "Protein aids in the formation of new tissues during healing." Protein is essential for wound healing as it plays a crucial role in cell growth and repair. It helps in the synthesis of collagen, which is important for tissue formation. Additionally, protein also helps in preventing infections during the healing process by supporting the immune system.