Final answer:
Crustaceans have an exoskeleton, gills, antennae, and swimming legs, with the exoskeleton being a distinctive feature that forms the carapace and is periodically shed to allow for growth.
Step-by-step explanation:
Crustaceans, such as shrimp and lobsters, are recognized by their possession of several characteristics; out of the options given, they all are correct. They have an exoskeleton that provides protection and structure, gills for respiration in the water, antennae for sensory input, and swimming legs that are often biramous, aiding in their locomotion in aquatic environments.
Specifically, the exoskeleton is a notable feature that may be bound together forming structures like the carapace. The carapace is a thick back shield covering the cephalothorax and often provides a protective space for the gills. Moreover, crustaceans periodically shed their exoskeleton in a process called molting, which allows them to grow since they cannot expand underneath the rigid exoskeleton.