The correct option is D diatomaceous earth
Diatoms have left behind a large amount of cell wall (SILICA) deposits in their habitat; this accumulation over billions of years is referred to as ‘diatomaceous earth’.
Capsomeres are the subunits that make up the 'capsid', an outer covering of viruses. Capsomeres are arranged in helical or polyhedral geometric forms.
The pellicle is a thin proteinaceous layer supporting the cell membrane in various protozoa, such as ciliates. It protects them and allows them to retain their shape, especially during locomotion.
Prions are infectious agents composed entirely of proteins. These proteins are called as prion proteins.