A nurse is mixing NPH insulin and regular insulin prior to administration. Which of the following actions should the nurse take first?

A. Inject air into the vial with NPH insulin in it: Air should be injected into the NPH vial after preparing the regular insulin to maintain proper technique, but it is not the first step in the process. B. Draw up the regular insulin dose: Drawing up regular insulin occurs after injecting air into both vials. Ensuring proper air injection first helps maintain accurate dosing and prevents a vacuum from forming in the vials. C. Inject air into the vial with regular insulin in it: Injecting air into the regular insulin vial is the first step in mixing NPH and regular insulin. This step equalizes pressure inside the vial, making it easier to withdraw the correct dose without contaminating or altering the insulin. D. Draw up the NPH insulin dose: Drawing up NPH insulin is done last to prevent contamination of the regular insulin with the intermediate-acting insulin. This ensures the correct order of mixing and maintains the integrity of both insulin types.