Is it true that there is no perfect conductor?

The statement that there is no perfect conductor is supported by the understanding that all materials inherently possess some degree of resistance to the flow of electric current. This intrinsic opposition to electron movement means that even the best conductors, such as copper or silver, will encounter some resistance, leading to energy loss in the form of heat.

In practical applications, while certain materials exhibit very low resistance (approaching ideal conductivity), it is impossible to eliminate resistance completely due to factors such as impurities in the material, lattice vibrations, or temperature fluctuations. Hence, while some materials are excellent conductors, none can achieve the status of a perfect conductor, maintaining that there is always some level of opposition present.

This context helps clarify why the other options do not hold true. There are no materials that can be classified as perfect conductors in any conditions, as all materials will show some resistance, albeit minimal in high-quality conductors or at low temperatures.