What is a coenobium?

Kelp (branched form) and Sargassum (filamentous form) belong to:

Identify the alga shown in the given figure.

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

In which of the following algal classes are starch and oil present as food storage materials?

In algae,sexual reproduction takes place through the fusion of two