Conductivity Thermal And Electrical

Step 1: Superconductivity.
Superconductivity refers to the phenomenon where certain materials, below a critical temperature, exhibit zero electrical resistance. This is a key property of superconductors, which allows them to conduct electricity without any loss of energy.

Step 2: Conclusion.
Therefore, the correct answer is that superconductors have zero electrical resistance below their critical temperature, corresponding to option (1).