Which of the following is an example of a crustacean?

The sowbug is an example of a crustacean because it belongs to a class of arthropods characterized by a hard exoskeleton, segmented body, and jointed legs. Crustaceans typically live in aquatic environments but can also be found in moist terrestrial habitats, like the sowbug, which is often found in leaf litter or soil. They possess two pairs of antennae and various body segments that give them their distinctive structure.

In contrast, the ant, centipede, and butterfly each represent different classes of arthropods. Ants are part of the insect class and lack the traits of crustaceans, such as the two pairs of antennae. Centipedes are myriapods and are distinct from crustaceans due to their long, segmented bodies and numerous legs, which do not conform to the crustacean structure. Lastly, butterflies are also insects, specifically in the order Lepidoptera, characterized by their wings and lifecycle, which again differentiates them from crustaceans.