The correct options are
A Diploblastic
B Body cavity is absent
D Presence of cnidoblast
The phylum Cnidaria is also known as Coelenterata. They are mostly marine animals which includes organisms like sea anemone, corals, hydras, jellyfish, etc. Cnidarians are diplobalstic, i.e., they have only two germ layers - endoderm and ectoderm. They are acoelomates - body cavity is absent. Their body shows radially symmetry. Another distinguishing character is the presence of cnidoblasts or sting cells.