Hydra can use its tentacles for

Hydra receives impulses and stimuli through

The sense organs of $Aurelia$ are known as:

Diploblastic animals belong to the phylum

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 $Euspongia$.

Which of the following is the larva of Cnidaria?