Correct Option: B

Cyanobacteria, e.g., Nostoc, grow in such abundance as to form water blooms. Sargassum belongs to brown algae which possess chl a, c, carotenoids, xanthophyll and a characteristic brown pigment, fucoxanthin. Commonly known forms of basidiomycetes are mushrooms, bracket fungi or puffballs. In Spirogyra gametes are non-flagellated (non-motile) but similar in size. They show amoeboid movements.