Materials exhibiting zero value of resistivity are known as ______ .

The correct answer is: D. superconductors.

Superconductors are materials that conduct electricity with no resistance. This means that if a current is passed through a superconductor, it will continue to flow indefinitely without any loss of energy. Superconductors are made from materials that have been cooled to very low temperatures, typically below -273 degrees Celsius.

Superconductors have a number of potential applications, including in power transmission, medical imaging, and particle accelerators. However, they are currently very expensive to produce and maintain, which has limited their widespread use.

Here is a brief explanation of each option:

• Conductors are materials that allow electricity to flow through them easily. Examples of conductors include metals, such as copper and silver.
• Semiconductors are materials that have electrical conductivity between that of a conductor and an insulator. Examples of semiconductors include silicon and germanium.
• Insulators are materials that do not allow electricity to flow through them easily. Examples of insulators include rubber and plastic.