Question

multiple choice question
what is the tunica externa of an artery made of?
connective tissue with irregular elastic and collagen fibers
a network of small capillaries
a thin serous membrane
endothelium

Explanation:

The tunica externa of an artery is the outermost layer. It is composed of connective tissue with irregular elastic and collagen fibers which provide strength and support to the artery. A network of small capillaries is not what the tunica externa is made of - these are vasa vasorum which supply blood to the artery walls. A thin serous membrane is not correct for the tunica externa. Endothelium is part of the tunica intima, the innermost layer of the artery.

Answer:

Connective tissue with irregular elastic and collagen fibers