How do conductors behave according to band theory?

According to band theory, conductors are characterized by having partially filled bands at low energy levels. This means that the electrons within these materials can move freely and easily, which is essential for electrical conduction. In a conductor, the valence band is typically partially filled or overlaps with the conduction band, allowing electrons to flow in response to an applied electric field.

This free movement of electrons accounts for the high electrical conductivity of metals and other conductive materials. The presence of partially filled energy bands signifies that there is no significant energy barrier to overcome for electron movement, leading to efficient conduction. This behavior contrasts with insulators and semiconductors, where energy gaps exist, hindering the flow of electrons. Thus, option B correctly reflects the nature of conductors in terms of band theory.