The correct answer is option 3: Lack of supply of blood to the heart itself. A heart attack, also known as myocardial infarction, occurs when there is a blockage in the coronary arteries that supply blood to the heart muscle. This blockage is usually caused by a buildup of fatty deposits called plaque. When the blood flow is reduced or completely blocked, the heart muscle doesn`t receive enough oxygen and nutrients, leading to damage or death of the muscle cells. This can result in chest pain, shortness of breath, and other symptoms. Bacterial attack (option 1) is not a cause of heart attack. While option 2 states "stopping of heart beat," it is worth noting that a heart attack can cause a disruption in the heart`s rhythm, but it is not the cause. Option 4, impairment of the heart`s functioning, is not the primary cause but can be a result of a heart attack.