The correct option is A Chrysophytes
The beautiful diatoms and desmids are placed under chrysophytes. Chrysophytes belong to kingdom Protista. The group contains about 5500 species. They occur in all aquatic and moist terrestrial habitats. The body is covered by a transparent siliceous shell (silica deposited in cell wall) known as frustule. The frustule is made up of two valves, epitheca, and hypotheca. The two valves fit together like a soapbox. Diatoms are very important photosynthesizers. They are very good pollution indicators.