Answer:
The correct option is : a. tunica intima
Explanation:
The blood vessels consists of the arteries, veins, arterioles, venules and the capillaries.
The capillaries are the thin and small blood vessels that connect the arteries to the veins. The capillaries are composed of only one tunica intima layer. The tunica intima is a thin layer which is composed of endothelium and connective tissues.
