A nurse is reinforcing teaching about insulin administration to a school age child who has diabetes mellitus. Which of the following instructions should the nurse include?

A. This statement reflects proper site rotation within a specific anatomical area. Rotating injections within the same general area (e.g., abdomen, thigh, upper arm) after 4–6 injections helps prevent lipohypertrophy while maintaining consistent absorption rates. Proper rotation within a single area is safer than frequently changing anatomical sites. B. Aspiration is not recommended for subcutaneous insulin injections because the risk of injecting into a blood vessel is extremely low and aspiration can increase pain or tissue trauma. C. Subcutaneous insulin should generally be injected at a 90-degree angle for most children and adults. A 30-degree angle is only used in very thin individuals to avoid intramuscular injection. Using a 30-degree angle routinely may reduce absorption consistency. D. Glargine (long-acting insulin) should never be mixed with other insulins in the same syringe because it alters its pharmacokinetics. Mixing can lead to unpredictable absorption and blood glucose fluctuations. Only certain short-acting and intermediate-acting insulins can be safely mixed if prescribed.