Which component is present in a normal sinus rhythm?

In a normal sinus rhythm, the presence of P waves, QRS complexes, and T waves is essential for indicating an effective and coordinated heart rhythm. P waves represent atrial depolarization, which is the initial electrical activity of the heart where the atria contract to fill the ventricles with blood. The QRS complex follows, representing ventricular depolarization, which is crucial for the ventricles to contract and pump blood to the lungs and the rest of the body. Finally, the T wave indicates ventricular repolarization, where the ventricles reset electrically in preparation for the next heartbeat.

This sequence—P wave followed by QRS complex and then T wave—reflects the normal conduction pathway and the order of heart electrical activity. A normal sinus rhythm is characterized by this complete cycle, highlighting that all three components are necessary for the heart to function properly. The absence of any of these components may suggest an abnormal rhythm or a cardiac issue, which is why the option containing all three elements is the correct answer.