You are presented with the quiz "what can be relaxed by dilation?" But you don't know the answer, so you turn to your teacher to ask for hints. He says that "dilation occurs when cell walls relax" and "an aneurysm is a dilation, or bubble, that occurs in the wall of an artery". So, what's the best answer to the question?

Available choices:
(A). artery
(B). alveoli
(C). the eyes
(D). the skin
(E). nerves
(F). sweating
(G). epidermal
(H). breathing
The answer is:
(A).