Correct Option: A

An obese person has a greatly increased number of blood vessels because of the amount of adipose tissue that must be serviced. As a result, the total length of his or her vascular tree is greatly increased and this person tends to have a higher blood pressure because of the greater resistance to blood flow. Resistance is inversely proportional to the fourth power of the radius of the blood vessel. In other words, the smaller the diameter of the vessel, the greater the resistance it offers to blood flow. If the radius of a blood vessel decreases by ½, its resistance to blood flow increases 16 times (½ x ½ x ½ x ½ = 1/16).