What type of tissue makes up the endothelium of capillaries?

In capillaries, the outer tunics of smooth muscle cells are absent and only the endothelium is present. Capillaries are often invested in pericapillary contractile cells called pericytes. The layer of endothelial cells is a type of epithelium and is bounded at its outer surface by a basement membrane.

i think it would be b. tissue because an organ system is a group of organs that work together to perform one or more functions. each does a particular job in the body, and is made up of certain tissues.

digestion

it excretes wastes