Final answer:
The most appropriate nursing response would be to reassure the client that their worth is not defined by their ability to have an erection.
Step-by-step explanation:
The most appropriate nursing response after a client with erectile dysfunction following a radical prostatectomy states, "I just don't feel like a man any more" would be:
C) "You're still a man, and your worth isn't defined by your ability to have an erection."
This response is empathetic and reassuring, emphasizing that masculinity is not solely determined by sexual function. It acknowledges the client's feelings while promoting a positive self-image and self-acceptance. It encourages the client to focus on other aspects of their life and relationships.