Which animal group besides Hydra also exhibits a diffused nervous system?

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A diffused nervous system, also known as a nerve net, is the simplest form of a nervous system found in multicellular organisms. It consists of interconnected neurons lacking a central brain or cephalization. This type of nervous system is characteristic of radially symmetrical animals, primarily belonging to the phyla Cnidaria (such as Hydra , jellyfish, and sea anemones) and Ctenophora (comb jellies). Mammals, birds, and insects possess a centralized nervous system with a distinct brain and nerve cords. Answer: C