According to the diagram below, which animal class has no tissue?
THE EVOLUTION OF ANIMALS
CNIDARIANS
SPONGES
FLATWORMS
ROUNDWORMS
RADIAL
SYMMETRY
TISSUES
THREE GERM LAYERS;
BILATERAL SYMMETRY
MULTICELLULARITY
SINGLE-CELLED ANCESTOR
MOLLUSKS
OPSEUDOCOELOM
PROTOSTOME DEVELOPMENT
ANNELIDS
COELOM
CHORDATES
ECHINODERMS
RADIAL
SYMMETRY
DEUTEROSTOME
DEVELOPMENT
A. Flatworms
B. Roundworms
C. Sponges
D. Cnidarians