Above diagram represents the band gap between valence band and conduction band for different types of material.
For conductor, both bands overlap each other. Therefore, band gap is zero. As Iron, Copper and Aluminium are conductors, therefore, band gap for these materials will be zero.
For semiconductor, there is very small band gap. Typically, band gap for semiconducting materials are less than 3.2eV . Hence, correct answer is Germanium, which is a semiconductor.
