Germ cells of Hydra are derived from

Which germ layer is absent in the phylum $Coelenterata$?

Bilateral symmetry does not occur in:

Which phylum exhibits tissue-level organization for the first time?

What are the functions of the tentacles in Phylum $Cnidaria$ (Coelenterata)?

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 $Euspongia$.