Which of these features is found only in arteries?

-elastic membranes
-vasa vasorum
-lumen
-valves

-elastic membranes  

Explanation:

The elastic membrane or tissue of the arteries allows the artery to bend and fit. It is important for artery to be elastic, because it transports oxygenated blood pumped from the heart to the tissues (except for pulmonary artery which carries deoxygenated blood) and thus have a blood pressure that is higher than in other parts of the circulatory system.

when atoms of different types of elements join together, they make molecules called compounds. water consists of compound molecules made up of 2 hydrogen atoms and 1 oxygen atom. this is why it's called h2o. water will always have 2 times the number of hydrogen atoms as oxygen atoms.