A nurse is caring for an adolescent client who has congestive heart failure and is taking digoxin daily. The client refused breakfast and is complaining of nausea and weakness. Which of the following actions should the nurse take first?

A. A dietitian consult can be considered, but it is not the priority. B. Requesting an antiemetic may be helpful for nausea but does not address the underlying cause. C. Checking vital signs is the priority as nausea and weakness can indicate digoxin toxicity, which can cause cardiac complications. D. Resting before eating does not address the potential for toxicity and other complications.