The correct answer is option 3: Hydra. Hydra is a small aquatic creature that belongs to the phylum Cnidaria. It is a multicellular organism that does not have blood like vertebrates do, but it does have specialized cells that help it respire. Hydra obtains oxygen for respiration through a process called diffusion. Diffusion allows oxygen to pass through the hydra`s body surface and reach its cells, where it is used in cellular respiration. While hydra does not have a circulatory system or blood vessels, it still takes in oxygen and releases carbon dioxide during respiration. Therefore, hydra is able to respire even though it lacks blood.