Final answer:
The nurse should explain the importance of privacy and personal relationships in maintaining overall well-being of the elderly couple, respecting their potential ongoing need for intimacy.
Step-by-step explanation:
The nurse should respond ethically and professionally to the staff member's assertion about the elderly couple's need for a shared room. The best response would be option (a), to explain the importance of privacy and personal relationships in maintaining overall well-being, which includes recognizing and respecting the couple's potential desire for intimacy, regardless of their age. By doing so, the nurse advocates for the couple's emotional and mental health and acknowledges that sexuality and the need for close relationships do not simply cease because of age.