The smallest blood vessel of the circulatory system is known as the _______ .
The correct option is B capillary
In our circulatory system, the artery divides into smaller and smaller vessels to bring the blood in contact with all the individual cells. These small vessels have walls which are one-cell thick and are known as capillaries. Exchange of material between the blood and surrounding cells take place across this thin wall. The capillaries then join together to form veins that carry the blood away from the organ or tissue.