Final answer:
The organism that has a dorsal nerve cord is the human, which is a chordate. The dorsal nerve cord differentiates to become the brain and spinal cord in vertebrates.
Step-by-step explanation:
The organism that possesses a dorsal nerve cord is B) human. A dorsal nerve cord is a unique feature found in the phylum Chordata, and it is one of the fundamental features that define members of this group. Humans, being part of the chordates, possess a dorsal nerve cord. This cord is a hollow tube located above the notochord, and it differentiates into the brain and spinal cord in vertebrates like humans. Other organisms like the hydra, paramecium, and earthworm do not belong to this phylum and therefore do not possess a dorsal nerve cord.
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