According to the research, the correct option is the RR interval must be absolutely constant. It is a characteristic of normal sinus rhythm.
<h3>What is arrhythmia?</h3>
It implies a disorder of the rhythm that makes it not stable or regular and is caused by a failure in the electrical system of the heart rhythm, called the excitation and conduction system.
In this sense, it implies a disorder in the systole of the heart affecting the sinus rhythm that is considered normal in relation to the heart when the RR interval, which is the distance between two successive R waves, is constant, when the waves deviate from sinus rhythm, it is probable that they reveal the existence of some cardiac pathology.
Therefore, we can conclude that according to the research, the correct option is the RR interval must be absolutely constant. It is a characteristic of normal sinus rhythm.
Learn more about arrhythmia here: brainly.com/question/13095303
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