Which group of animals has joined legs and cellulose skin?

• A. Arthropods
• B. Amphibians
• C. Reptiles
• D. Aquatic animals

Answer: (A)

Jointed legs with an external protective covering define this group. Arthropods have limbs that are true joints, allowing a wide range of precise movements, and they wear an external skeleton made of chitin. This combination—jointed appendages plus an outer exoskeleton—sets them apart from the other groups listed.

Amphibians and reptiles are vertebrates, meaning their limbs are connected to an internal skeleton, and their skin is not a rigid exterior shell. The broad category of aquatic animals includes many organisms without jointed legs or hard exoskeletons, so they don’t share this characteristic either. Also, the reference to a “cellulose skin” isn’t accurate for animals—the external covering of arthropods is chitin, not cellulose.

So the group that matches the description of jointed legs and an external shell is the arthropods.