Final answer:
The nurse should determine that teaching is effective based on the client's statement: "I will rotate injection sites within the same area."
Step-by-step explanation:
The nurse should determine that teaching is effective based on the client's statement:
C) "I will rotate injection sites within the same area."
This statement shows that the client understands an important aspect of self-administering insulin. Rotating injection sites within the same area helps prevent tissue damage and ensures consistent absorption of insulin.