Why Is Silicon Not Suitable for Making Covalent Bonds Stable

Why is silicon not suitable for making covalent bonds stable and strong enough to form the basis of living organisms, even though it is just below carbon on the periodic table?

A) Silicon is too large for its nucleus to attract the valence electrons of neighboring atoms in order to form covalent bonds.
B) Silicon is too small for its nucleus to attract the valence electrons of neighboring atoms in order to form covalent bonds.
C) Silicon is too large for its nucleus to attract the protons of neighboring atoms in order to form covalent bonds.
D) Silicon is too small for its nucleus to attract the protons of neighboring atoms in order to form covalent bonds.