Silica gel is obtained by
a)	Red algae	b)	Diatoms	c)	Euglena	d)	Mycoplasma

(b)

The siliceous cell walls of diatoms are indestructible (i.e., do not decay easily). They were collected over millions of years on the sea floors, called diatomite or diatomaceous earth or silica gel. These deposits may extends for several hundred metres in certain areas