Which animal possesses neurons but lacks a brain?

Which type of larva is found in the phylum $Cnidaria$?

Radial symmetry is observed in . . . . . . .

Which of the following is a characteristic feature of the phylum $Coelenterata$ (Cnidaria)?

Which of the following is a $Coelenterate$?

Which of the following statement$(s)$ is/are correct regarding phylum $Coelenterata$ (Cnidaria)?
$(A)$ They are aquatic,mostly marine,sessile or free-swimming,radially symmetrical animals.
$(B)$ They have a central gastro-vascular cavity with a single opening on hypostome.
$(C)$ Digestion is extracellular and intracellular.
$(D)$ Their members are $Sycon$,$Spongilla$ and $Euspongia$.