b$)$ Using the cases presented in the schematics for the different electronic band structures Figure $2$ below, identify the relevance of each band structure to a specific material type and discuss how electronic conductivity may or may not occur.

$($a$)$

$($b$)$

$($c$)$

$($d$)$

Figure $2$ Electronic band structures for different materials.

In addition to band structure, what other factors influence conductivities in cases $($c$)$ and $($d$)$ above.