Which of the following correctly explains a phase/ event in the cardiac cycle in a standard electrocardiogram?
(a) QRS complex indicates atrial contraction.
(b) QRS complex indicates ventricular contraction.
(c) The time between S and T represents atrial systole.
(d) P-wave indicates the beginning of ventricular contraction.
The answer is the option (b) QRS complex indicates ventricular contraction
Explanation: QRS wave starts with a downward deflection and continues as an upright triangular wave with downward waves as its base. It indicates ventricular depolarization or contraction.