Diffusion? are you asking what its called?
Answer:
b. help retain moisture in terrestrial habitats
Explanation:
Arthropods such as cockroach, centipedes, spiders, crab are the members of the largest phylum Arthropoda. These are animals with paired jointed legs and their body is covered with an exoskeleton made of chitin. They live in diversified habitat and exoskeleton helps to retain moisture in theterrestrial habitats.
Similarly mollusks such as sepia, snail are soft bodied animal whose body is covered with calcareous shell as a protection and to retain moisture while living on land.
