A is your answer.
Water containing no salt is known as isotonic solution
Organic molecules, which are found mostly in food. These molecules have C-C or C-H bonds, which are high energy bonds.
In a typical ECG (Electrocardiogram) the first wave obtained is P wave; The P wave represents the depolarization of the atria. After this, the QRS complex is formed. The QRS wave represents the depolarization of the ventricles. During the depolarization phase, the ventricles contracts and pushes the blood into the atria. Hence, the correct answer is depolarization of the ventricles.
