Your answer would be C.It encloses the cytoplasm.
The alveoli are surrounded by tiny blood vessels, called capillaries carrying blood to and from the heart.
Caro means expensive in spanish
Polystyrene is a good insulator as it has small air bubbles trapped inside of it. This means heat energy cannot flow through them therefore it is an effective material for keeping honeybees warm in the winter. Hope this helps :)
