Silicon is the . . . . . . . . most abundant element in the earth's crust.

Answer: Option D

Silicon is the chemical element with atomic number 14. It is a hard, brittle crystalline solid with a blue-grey metallic luster.
It is the second most abundant element in the earth’s crust after oxygen.
It is relatively unreactive, but it shows a high affinity toward oxygen, it links up with oxygen to form the most common minerals on Earth.