The correct answer is: D. Electrolytes
Electrolytes are substances that, in solution or when molten, allow the passage of an electric current. They are made up of ions, which are atoms or molecules that have a positive or negative charge. When an electric current is passed through an electrolyte, the ions move towards the oppositely charged electrode. This movement of ions is what allows electricity to flow through the electrolyte.
The conductivity of an electrolyte is affected by temperature. In general, the conductivity of an electrolyte increases with increasing temperature. This is because the higher temperature causes the ions to move more quickly, which increases the rate of current flow. However, there are some electrolytes that have a negative temperature coefficient, meaning that their conductivity decreases with increasing temperature. This is because the higher temperature causes the ions to become more hydrated, which makes it more difficult for them to move.
Compounds of silver, liquid metals, and metallic alloys are all conductors of electricity. However, their conductivity is not affected by temperature in the same way as that of electrolytes. The conductivity of these materials increases with increasing temperature, but the rate of increase is not as great as that of electrolytes.
Therefore, the correct answer is: D. Electrolytes