Final answer:
The correct action for the nurse is to administer antihypertensive medication as prescribed to manage the patient's elevated blood pressure in the context of an abdominal aortic aneurysm.
Step-by-step explanation:
The question relates to the care of a patient with an abdominal aortic aneurysm who has an elevated blood pressure of 160/98 mm Hg and is scheduled for surgery. As a nurse, the appropriate action to take would be to administer antihypertensive medication as prescribed. This is crucial because managing the patient's blood pressure is important to reduce the risk of rupture of the aneurysm. Documentation of the findings alone (option B) is not sufficient, preparing the patient for immediate surgery (option C) might not be required based on vital signs alone, and reassuring the patient that these signs are expected (option D) does not address the elevated blood pressure and heart rate.