A Patient's Cardiac Monitor Shows a Rate of 89 with a PR

A patient's cardiac monitor shows a rate of 89 with a PR interval of 0.2 second and a QRS of 0.10 second. What is the most important nursing action?

A) Start the patient on O₂ at 4 L/min via nasal cannula.
B) Obtain a 12-lead ECG immediately.
C) Report these abnormal findings to the health care provider.
D) Continue to monitor the patient's cardiac status.