The most appropriate term to designate the life cycle of $Obelia$ is

The main cavity in the body of $Hydra$ is called:

Which of the following phyla includes both freshwater and marine species?

Which form in Phylum $Cnidaria$ is free-swimming?

Identify the correct features for $Medusa$ and $Polyp$ forms in Phylum $Coelenterata$ (Cnidaria) from the given list:
$I$ - $Sessile$
$II$ - $Umbrella-shaped$
$III$ - $Free-swimming$
$IV$ - $Produced$ $by$ $asexual$ $reproduction$
$V$ - $Cylindrical$
$VI$ - $Produced$ $by$ $sexual$ $reproduction$
$Medusa$ $\quad\quad$ $Polyp$

Which of the following is true for the polyp form of Coelenterata (Cnidaria)?