Which phylum consists of animals that exhibit radial symmetry?

Which one of the following animals possesses nerve cells but no nerves?

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

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

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

Which phylum of animals exhibits tissue-level body organization?