`C` and `Si` both have same lattice structure, having `4` bonding electrons in each. However, `C` is insulator whereas `Si` is intrinsic semiconductor. This is because
A. The four bonding electrons in the case of `C` lie in the thirtd orbit, whereas for `Si` they lie in the fourth orbit
B. In case of `C` the valence band is not completely filled at absolute zero temperature
C. In case of `C` the conduction band is partly filled even at absolute zero temperature
D. The four bonding electrons in the case of `C` lie in the second orbit, whereas in the case of `Si` they lie in the third orbit
