Carbon, silicon and germanium have four valence elements each. At room temperature which one of the following statement[s) is most appropriate ?

The number of free electrons for conduction is significant in all the three

The number of fee electrons for conduction is significant only in Si and Ge but small in C

The number of free conduction electrons is significant in C but small in Si and Ge

The number of free conduction electrons is negligibly small in all the three