Which characteristic accurately describes a normal sinus rhythm?

A normal sinus rhythm is characterized by specific features that collectively indicate the heart is functioning properly. The heart rate in a normal sinus rhythm typically falls within 60 to 100 beats per minute, which reflects the ability of the sinus node to generate electrical impulses effectively. This heart rate range is crucial because it ensures that the heart is pumping blood adequately to meet the body's needs during rest and activity.

The QRS complex duration, which represents the time it takes for the ventricles to depolarize and contract, is normally between 0.06 to 0.10 seconds. While a duration of 0.08 seconds is within the normal range, it is not standard to state that a duration of 0.12 seconds would be associated with a normal sinus rhythm. In this context, a 0.08-second QRS duration would be considered normal as well.

The mention of a 20 mm amplitude is also part of the normal sinus rhythm in terms of the physical measurement of the electrical activity. However, amplitude can vary based on multiple factors including body position and electrode placement and is not typically specified as a standard feature of a normal sinus rhythm.

Since the question states that all these aspects together describe a normal sinus rhythm, selecting that option reflects