How does the structure of the alveoli allow for its function of gas exchange?
a. alveolar sacs produce mucus that makes gas exchange easier.
b. alveolar sacs rely on valves to ensure that air flows only in one direction.
c. alveolar sacs are located within muscles that contract, which increases gas exchange.
d. alveolar sacs are surrounded by thin capillaries where gases can be exchanged.

The correct answer would be D.Alveolar sacs are surrounded by thin capillaries where gases can be exchanged.

Alveoli are tiny sacs which form the site of gas exchange in the lungs.

The features of alveoli which help in gas exchange are:

b would be the right answer

prophase: we can observe the chromosomes to coil up and condense. they become visible. nuclear membrane and envelope disintigrate.s

metaphase: chromosomes align at the center, the metaphase plate. spindle fibers attach to centromeres of the sister chromatids. they meet at kinetochores.

anaphase: sister chromatids are pulled towards each opposing centromere, set on different poles.

telophase: chromosomes are now clustered up only on either sides of the cell. nuclear membranes reform, and a new cell wall forms along the cell plate. this will lead to cytokinesis, the process that divides the cell membrane and forms the cell wall.