A nurse is caring for a client who has a prescription for NPH insulin 10 units and regular insulin 15 units subcutaneously. After injecting 10 units of air into the NPH insulin vial, which of the following actions should the nurse take next?

Choice A reason: Injecting 15 units of air into regular insulin balances vial pressure, per protocol. This step precedes drawing regular insulin, ensuring accurate mixing sequence.Choice B reason: Withdrawing NPH now skips regular insulin prep, risking contamination or error. Air injection into both vials comes first in standard insulin administration.Choice C reason: Verification is key but follows insulin preparation. Air injection sequence precedes dosage checks, making this premature before completing vial prep steps.Choice D reason: Capping the needle halts the process prematurely. Air must be injected into both vials first to maintain sterile technique and accurate dosing.