Which Characteristic(s)is (Are)shared by Both Cnidarians and Flatworms

Question

Which characteristic(s)is (are)shared by both cnidarians and flatworms?
A)dorsoventrally flattened bodies
B)true muscle
C)radial symmetry
D)a digestive system with a single opening
E)two of these

Accepted Answer

Both cnidarians and flatworms have a digestive system with a single opening (known as a gastrovascular cavity in cnidarians and a gastrodermis in flatworms). They do not have a separate mouth and anus.