Resistance is depends on temperature. If temperature is increase, resistivity will increase. Increase in resistivity will leads to decrease in conductivity. The relation is given below.

Where →resistivity

σ →Conductivity

The product of resistivity and conductivity is not depend on temperature. Because resistivity and conductivity of a metallic resistor are nullifying the change in the temperature.

If the temperature of a metallic resistor is increased, the product of its resistivity and

Conductivity may increase or decrease. Option D is correct.