A nurse is reviewing a client's ECG rhythm strip. Which of the following components should the nurse use to measure impulse conduction from the sinus node through the atrioventricular node?

A. The ST segment represents the time between ventricular depolarization and the beginning of repolarization. It does not measure conduction through the atria or AV node. B. The PP interval measures the distance between atrial depolarizations (P waves) and is used to assess atrial rhythm, not conduction time. C. The PR interval measures the time from the beginning of atrial depolarization (P wave) to the beginning of ventricular depolarization (QRS complex). It reflects impulse conduction from the sinus node through the atria, AV node, and His-Purkinje system, making it the correct answer. D. The QRS complex represents ventricular depolarization, not the conduction time through the atria or AV node.