The correct option is C.
Diatoms are unicellular, eukaryotic, photosynthesizing algae that possess silical gel wall. The habitats, where they could be found include: fresh water, marine water, soils and most moist places. They are autotrophic in their mode of feeding and thus they are usually found in the photic zones in water bodies. The plant exist as a single cell but many cells can also join together to form a colony.
