Like Carbon, Silicon Can Form Complex Molecules Yet Silicon-Based Life

Like carbon, silicon can form complex molecules yet silicon-based life has not been found. Why not?

A) Carbon preferentially displaces silicon in extensive polymers.
B) Silicon atoms are not present in the lithosphere at high enough concentrations.
C) The covalent bonds between silicon atoms yield less energy when oxidised.
D) The oxide of silicon is a liquid.
E) Silicon is not a tetravalent atom.