Final answer:
B. millipede. The animal described is most likely a millipede. Millipedes have two pairs of legs per segment and feed on leaf litter and organic material.
Step-by-step explanation:
The animal described in the question with a long segmented body, about 60 pairs of jointed legs, and an exoskeleton is most likely a millipede (option B). Millipedes have two pairs of legs per segment, and their bodies are divided into many segments. They are herbivores or detritivores, feeding on leaf litter and organic material. In contrast, centipedes (option A) have one pair of legs per segment and are predatory.