= Solution
{c}
The lower curve is a <valence band> and the upper curve is a <conduction band>, separated by an indirect <band gap>. The readable upper curve has a minimum just inside the X boundary and slightly below the plotted <chemical potential>. It is therefore partially occupied, while the visible valence states lie below the <chemical potential> and are filled at low <temperature>. The sample is electron-doped, with <electron pockets> around the six symmetry-related conduction minima of <silicon>.
The full high-symmetry path and part of the lower-left dispersion are absent from the held image. \b[Source gap:] those missing path labels and curve segments cannot be read or reconstructed from this copy. The identification of the conventional six silicon valleys and the valence maximum at $\Gamma$ uses the usual <silicon> band model, rather than purported readings of missing pixels.
Two methods for calculating such an <electronic band structure> are <density functional theory>, solving a self-consistent periodic electronic problem, and a <tight-binding model>, diagonalizing a hopping Hamiltonian built from localized <atomic orbitals>. Neither is a measurement of the plotted <dispersion relation>.
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