A 52-year-old man presents with symptoms of shortness of breath and tachycardia. He denies experiencing any chest pain. He reports that he was being managed for hypertension but elected to stop taking his medications a few months ago in favor of a homeopathic remedy. His ECG is shown. The ECG best supports a diagnosis of:
a) Myocardial infarction.
b) Left ventricular hypertrophy.
c) Atrial fibrillation.
d) Left atrial enlargement.