Final answer:
The nurse's most appropriate response is to acknowledge the emotional difficulty of the situation with option (a) "That must be very difficult for you."
Step-by-step explanation:
The most appropriate response by the nurse in this scenario is option (a) "That must be very difficult for you." This empathetic statement acknowledges the client's emotional state and opens the door for further discussion, thereby validating the client's feelings about the news of an amputation. Choices (b) and (d) are less effective as they either divert the focus to the doctor or express pity, which might not be what the client made clear they were looking for. Option (c), "Tell me more..." while open-ended, may not be appropriate as it requires more emotional effort from the client immediately after receiving difficult news.