Option B is correct because insects belong to the phylum Arthropoda, which is defined by having jointed appendages (legs). The context explicitly states that 'Arthropods (arthro means limbs and poda means appendages) includes insects'. In contrast, earthworms belong to the phylum Annelida, which have cylindrical and segmented bodies but lack jointed legs. Option C (cylindrical body) is a characteristic of earthworms, not insects, while Options A and D do not specifically confirm the animal is an insect over an earthworm.