Final answer:
Cardiac diastole on an ECG is not represented by the P wave, QRS complex, or T wave, as atrial repolarization is masked by the QRS complex. Therefore, the correct answer is 'none of the above'.
Step-by-step explanation:
Cardiac diastole refers to the period during which the heart muscle relaxes. In an ECG, the cardiac diastole corresponds to the time when both the atria and ventricles are at rest. Initially, the diastolic phase begins with the end of the T wave, which represents the repolarization of the ventricles, and continues until the start of the next P wave. The QRS complex is associated with the depolarization of the ventricles and the beginning of the ventricular contraction (systole), and it occurs after the atria have relaxed. Therefore, the correct answer to the question would be 'none of the above' since atrial repolarization, which takes place during ventricular depolarization, is masked by the QRS complex and is not distinctly represented on an ECG.