The correct option is A Bacillariophyceae
Cells of diatoms (Bacillariophyceae) are surrounded by the cell wall, deposited with silica called as frustules which are composed of two overlapping halves (the epitheca and the hypotheca). Shells of diatoms are highly resistant to decomposition due to the presence of silica and are deposited in ocean beds leading to the formation of the diatomaceous earth. Thus, the correct answer is option A.