Carbon, silicon, and germanium have four valence electrons each. At room temperature, which one of the following statements is most appropriate?
| A. |
The number of free conduction electrons is negligibly small in all the three. |
| B. |
The number of free electrons for conduction is significant in all the three |
| C. |
The number of free electrons for conduction is significant only in Si and Ge but small in C. |
 |
| D. |
The number of free conduction electrons is significant in C but small in Si and Ge. |