The correct answer is (c). Hydra and sea anemone are both members of the phylum Coelenterata. They are radially symmetrical animals with a simple body plan that consists of a central mouth surrounded by tentacles. They have a single opening for both eating and excreting waste. Coelenterates are also known for their stinging cells, which they use to capture prey.
Planaria and liver fluke are both members of the phylum Platyhelminthes. They are flatworms with a bilaterally symmetrical body plan. They have a digestive system with a mouth, an esophagus, and a gut. They are also parasitic, meaning that they live on or in other organisms and feed on their tissues.
Sea urchin and sea cucumber are both members of the phylum Echinodermata. They are radially symmetrical animals with a hard outer skeleton. They have a water vascular system that they use for movement and respiration. Sea urchins are also known for their sharp spines, which they use for protection. Sea cucumbers are known for their long, flexible bodies, which they use to move through the sand.
Euplectella and sycon are both members of the phylum Porifera. They are sponges with a porous body. They have a simple body plan that consists of a network of canals through which water flows. Sponges are filter feeders, meaning that they collect food particles from the water.
In conclusion, the correct answer is (c). Hydra and sea anemone are both members of the phylum Coelenterata.