Which of the following statements is correct about the conduction of electricity in pure crystal of silicon atroom temperature?
(1) The conduction is due to electrons present in fully occupied lowest energy states.
(2) The conduction is due to only some electrons capable of leaving the bonds at room temperature.
(3) The conduction is only due to the holes formed from the release of electrons.
(4) The conduction is due to the movement of both the electrons released and holes formed.