Final answer:
A PJC would not display the characteristic atrial repolarization because it is masked by the ventricular depolarization visible in the QRS complex on an EKG.
Step-by-step explanation:
A PJC (premature junctional contraction) is a type of arrhythmia that originates from the atrioventricular junction of the heart. When considering an EKG, there are five prominent points typically displayed: the P wave, the QRS complex, the T wave, and occasionally, the U wave. The P wave represents the depolarization of the atria, the QRS complex represents the depolarization of the ventricles, and the T wave represents the repolarization of the ventricles. The repolarization of the atria happens during the QRS complex, which masks it on an ECG. Thus, in the context of the provided options, a PJC would not display characteristic d) none of the above: atrial repolarization is masked by ventricular depolarization.