Answer
See the answer below.
Work Step by Step
Above 0 K, some electrons will be promoted to higher energy levels creating two singly-occupied orbitals per electron moving, one where it came from and one where it went to. The "hole" in the orbital previously occupied creates a relative positive charge in relation to the other electrons, while the newly occupied orbital gets a negative charge. Conductivity exists because electrons move away from the newly added negatively charged orbital and towards the relatively positive charged orbital.
