The normal systolic pressure in human beings is :

The correct answer is C, 120 mm of Hg. Blood pressure is written as two numbers, and normal adult blood pressure is about 120/80 mm of mercury. The upper figure, systolic pressure, is the pressure in the arteries when the ventricles contract and push blood out; the lower figure, diastolic pressure, is the pressure when the heart relaxes between beats. It is measured with a sphygmomanometer, usually on the brachial artery of the upper arm. Readings that stay at 140/90 or above are generally treated as high blood pressure (hypertension). Option A is wrong because 80 mm of Hg is the normal diastolic pressure, not the systolic. Option B is wrong because 100 mm of Hg is below the normal systolic value. Option D is wrong because a systolic reading of 140 mm of Hg is the usual threshold for hypertension. Exam tip: normal BP = 120/80 mm Hg (systolic/diastolic), measured by a sphygmomanometer.