Hint: The difference between the systolic and diastolic blood pressure is known as pulse pressure. It is measured in millimetres of mercury (or mmHg). Doctors use this as an indicator of how well a heart is working.
Complete answer: The normal pulse pressure of a human being is about 40 mmHg. At rest position, a normal young adult will have a stroke volume of about 80 mL. 2 mL/mm Hg is the arterial compliance, which makes it clear that the normal pulse pressure is 40 mm Hg. Pulse pressure is the force that the heart generates every time it contracts. The normal blood pressure of a person is 120/80 millimetres of mercury (or mmHg). The upper number of the blood pressure is the atmost pressure our heart can exert while beating (systolic pressure) whereas the lower number of the blood pressure is the pressure present in our arteries between the beats (diastolic pressure). Hence the difference between the two is 40 mm/Hg. Hence,option A: 40 mm/Hg is the correct answer.
Note: Blood pressure indicates whether our heart is at the risk of heart stroke or not. If the pulse pressure is more than 60 mm/Hg, then the heart is at great risk of cardiovascular disease, especially in older people. Hence, to keep our heart safe from diseases, we must stop smoking, do regular exercise and reduce the amount of pressure in the food we eat.