Which of the following correctly describes the structure and function of tissue layers found in blood arteries and veins?

Tunica media; contains muscle that constricts the vessels to increase blood flow

Tunica media; contains connective tissue that provides structural support

Tunica externa; contains connective tissue that provides structural support and elastin that prevents backflow

Tunica externa; contains muscle that constricts the vessels to increase blood flow and elastin that prevents backflow