A nurse is providing teaching to a client who has a new diagnosis of type I diabetes mellitus about administering NPN insulin and regular insulin together in one injection. Which of the following instructions should the nurse include?

A. Roll the syringe gently to ensure mixture of the insulins: Insulin should be mixed by rolling only the vial of NPH, not the syringe. After drawing both insulins into one syringe, gentle rolling is not typically done with the syringe itself to mix them. B. Inject into the vastus lateralis: The vastus lateralis is typically used for IM injections. Subcutaneous tissue of the abdomen or thigh is preferred for insulin injections for better absorption. C. Use a 15° angle for the injection: A 15° angle is used for intradermal injections. Insulin should be given subcutaneously using a 45° or 90° angle depending on needle size and fat thickness. D. Draw up regular insulin prior to NPH insulin: Regular insulin should always be drawn up first to prevent contamination of the clear insulin with the cloudy NPH insulin, maintaining efficacy and correct dosing.