Answer:
The correct answer is option A.
Explanation:
An electrocardiogram or ECG is a test that helps in measuring and representing the electrical activity of the heartbeat on a graph. A wave or electrical impulse runs through the heart with each beat that leads to the muscles to squeeze and pumps the blood from chambers of the heart.
The point that is indicated in the graph is P wave which describes the depolarization of the muscles of the atria which results in the contraction of the atrial muscles or atrial systole.
Thus, the correct answer is option A.