The correct answer is option (B) diatoms.
Diatoms are the photosynthetic, single celled algae found in oceans with a characteristic skeleton made up of the silica having a huge fossil deposits. These fossilized remains of the diatoms are called diatomaceous earth or diatomite. This siliceous sedimentary rocks of diatoms are converted to a powdery mass and used for many purposes.
The Diatomite is widely used as an insecticide. It is used against members of arthropods like insects, molluscs like slugs. In the members of arthropods, the diatomite powder absorbs the lipids from the exoskeleton of the organisms making it vulnerable to the evaporation of water or water loss from the body. It is also used in the control of ants, cockroaches, mites, bed bugs, bettles and other organisms. It can also reduce the fleas and parasites on other animals.