True statements about ECG include:
a. the P-R interval corresponds to the duration of atrial systole
b. the T-wave ends at the time of aortic valve closure
c. the ST segment represents repolarization of the ventricles
d. all
a. the P-R interval corresponds to the duration of atrial systole
b. the T-wave ends at the time of aortic valve closure
c. the ST segment represents repolarization of the ventricles
d. all