Carrageenin,a jelly-like substance,is obtained from:

$A$ : Thallophytes are non-vascular,non-archegoniate and non-cormophytic plants.
$R$ : Thallophytes lack vascular bundles,archegonia and differentiated plant body.

The thallus organisation of $Volvox$ is

Agar-agar is obtained from

Identify the plant shown in the given figure.

Pyrenoids in green algal cells are related to