Final answer:
The nurse will document the administration of medication in the Medication Administration Record (MAR) immediately after administering the medication to the client with high blood pressure.
Step-by-step explanation:
The nurse will document the administration of medication in the Medication Administration Record (MAR) immediately after administering the medication to the client with high blood pressure. The MAR is a legal document that serves as a record of all medications given to a patient, including the date, time, medication name, dosage, and route of administration. By documenting the administration in the MAR, the nurse ensures accurate recording, accountability, and continuity of care.