Polyp phase is absent in $....$

Which of the following cells are present only in the epidermis of Hydra?
$(A)$ Interstitial cells
$(B)$ Cnidoblasts
$(C)$ Sensory cells
$(D)$ Germ cells

$A$ coelenterate commonly known as 'fresh water polyp' is

Corals belong to the phylum . . . . . . .

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

In the phylum $Coelenterata$ $(Cnidaria)$,what are the sequential names of the asexual and sexual stages?