1. We are asked to identify the type of solid which:

   • is not transparent to visible light, and
   • has conductivity increasing with temperature.

2. Let us analyze the given properties.

   Property 1: Conductivity increases with temperature

   This is a characteristic of semiconductors.

   For semiconductors, as temperature increases, more charge carriers are generated, so conductivity increases.

   In contrast, for metals, conductivity generally decreases with temperature due to increased lattice scattering.

3. Now consider which bonding is associated with semiconductors.

   Common semiconductors such as Si and Ge are solids with covalent bonding.

4. Check the other options:

   • A: Ionic bonding
     Ionic solids are generally insulating in solid state and do not show typical semiconductor behavior.

   • B: Covalent bonding
     Covalent solids like silicon and germanium are semiconductors. They are not transparent to visible light in the usual sense and their conductivity increases with temperature.

   • C: Vander Waals bonding
     Molecular solids with van der Waals bonding are generally insulators.

   • D: Metallic bonding
     Metals are not transparent, but their conductivity decreases with temperature, so this does not match.

5. Therefore, the solid described must be formed by covalent bonding.

$\boxed{\text{Option B}}$