In the electrocardiogram, the

A. False The electrical event precedes the mechanical event.

B. True This electrical event corresponds with ventricular relaxation.

C. False It corresponds to the interval between atrial and ventricular depolarization due to delay of the impulse in the AV bundle.

D. True R indicates the beginning, and T the end, of the ventricular action potential.

E. True Due to the heart rate changes associated with respiratory sinus arrhythmia.