The exoskeleton of an arthropod is chitin.
Explanation:
if you were trying to find the function of something it you would mainly think of roles, jobs, responsibilities, chores etc, where as if you were trying to find the structure it would be how something is made up or its form.
for example the srtucture of a plant, meaning its form or how it grew, its function depends on what type of plant, if it were just a regular plant or leaf, the stomata, cell wall, cell membrane, nucleus, chloroplasts, chlorophyll inside the chloroplasts, mitochondria, cytoplasm, would be requied to do their funtions i.e their jobs to keep the plant/leaf alive
I think the correct answer from the choices listed above is option B. A modification of the leaves into the spine in a cactus plant can be seen The spines are modified leaves. It helps defend the plant and also reduce the surface area which helps limit loss of water.
