Concept:Metals have a positive temperature coefficient of resistance.
Explanation:In metals, heating increases the vibration of atoms in the crystal lattice.
This causes more frequent collisions between free electrons and vibrating atoms.
As a result, the resistance of a metal increases when temperature rises.
In contrast, water and electrolytes conduct better at higher temperatures, so their resistance decreases.
Wood does not show the same metallic positive temperature response.
Therefore, the material whose resistance increases with temperature is a metal.
Answer:B. metals