What is the band gap energy for an insulator in $eV$?

If $V_0$ is the volume of a standard unit cell of germanium crystal containing $N_0$ atoms,then the expression for the mass $m$ of a volume $V$ in terms of $V_0, N_0, M$ and $N_A$ is [here,$M$ is the molar mass of germanium and $N_A$ is the Avogadro's constant].

Although carbon,silicon,and germanium have the same lattice structure and four valence electrons each,their band structure leads to the energy gaps as:

Which graph shows correctly the temperature $(T)$ dependence of resistivity $(\varrho)$ of a semiconductor?

In the energy band diagram of insulators,the band gap and the conduction band are respectively:

In a semiconductor,