The correct option is D Radial symmetry
Cnidaria or Coelenterata are radially symmetrical with tissue level of organisation and diploblastic in nature. They are devoid of coelom or body cavity.
Organisms in phylum Platyhelminthes and onwards, are triploblastic with bilateral symmetry. Organisms in phylum Platyhelminthes have organ level of organisation. Phyla after Platyhelminthes have organ system level of organisation.
Phylum Annelida and onwards have true coelom.