Answer:
The main function is protection, breathing and support.
Explanation:
An exoskeleton covers the entire surface of arthropod animals, such as arachnids, insects, crustaceans, etc. Its main function is the protection, breathing and support of the muscular system, favoring its fossilization.
Answer: D
Why? a, b, and c will not make it so you can see the organisms cells. However, Using a microscope you can do the answer is D.
Hope this helps :D