In what case would P waves be visible in a junctional rhythm?

In a junctional rhythm, the P waves may not be visible or could be altered due to the heart's electrical conduction originating from the junctional area (the AV junction). This area is located near the atrioventricular node, which can lead to scenarios where the P waves are either hidden within the QRS complex or not present at all.

In this context, the correct answer highlights the possibility that P waves can be obscured or masked during the QRS complex, making them difficult to distinguish. This occurs because when the impulse is generated from the junction, the atria and ventricles may contract almost simultaneously, causing any existing P waves to be overshadowed by the ventricular depolarization represented by the QRS.

Other options imply more definitive states of visibility or polarity of the P waves that are not consistent with the nature of the junctional rhythm, where P waves can vary in appearance and may not always manifest clearly or consistently. Understanding this aspect helps clarify the complex dynamics of cardiac rhythms and pacing origins.