= Solution
\b[HgS and $\mathrm{C_3N_4}$ are semiconductors; $\mathrm{Hg(SCN)_2}$ is a wider-gap, insulating material under the stated conditions. None is a metallic conductor.] Their finite electronvolt-scale gaps and very low measured conductivities exclude a partially filled, highly conducting metallic band picture.
The insulator/semiconductor boundary is conventional rather than a sharp universal gap cutoff. Calling the $3.2\,\mathrm{eV}$ material a <wide-bandgap semiconductor> is also physically reasonable; the table alone does not establish a unique naming boundary. Conductivity is $\sigma=e(n\mu_n+p\mu_p)$, so its ordering need not follow gap size alone: carrier density, defects, trapping and mobility also matter.
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