Name the two animal phyla which exhibit radial symmetry.

• The cnidarians and the echinoderms retain the radial harmony.
• Cnidarians are also called coelenterate that belong to the phylum Cnidarian (Coelenterate). 
• This phylum comprised 9000 living species. 
• Generally, in marine creatures, the cnidarians include the corals, hydras, doormat, Portuguese men- of- war, ocean anemones, jelly fish, ocean pens, ocean lashes, and ocean suckers.
• Cnidarians are radially indeed and they don't retain cephalization (confluence of sensitive organs in a head), their bodies have two cell layers rather of the three like the advanced creatures.
• And they retain the saclike coelenteron body that has only opened (the mouth). Cnidarians have two body structures — neoplasm and medusa which constantly be in its life cycle. 

Hence, option D is the correct answer.