A nurse is planning to administer a controlled substance to a client who is experiencing pain. Which of the following actions should the nurse plan to take first?

The correct answer is B: Identify the client using two identifiers. This is the first step the nurse should take to ensure the right medication is given to the right patient, following the principles of medication safety. By verifying the client's identity using two identifiers (such as name and date of birth), the nurse can prevent medication errors and ensure patient safety. Removing the medication (A) is important but should only be done after confirming the patient's identity. Comparing the medication amount to the inventory record (C) is a later step in the medication administration process. Documenting the administration (D) is essential but should come after verifying the patient's identity.