What is considered the poorest conductor of electricity?

Distilled water is considered the poorest conductor of electricity among the options provided. The reason for this is that distilled water is largely purified, meaning it has most of its ions removed, specifically those that can facilitate the flow of electric current. In its purified state, distilled water has very few charged particles (ions) that can move freely to conduct electricity, which makes it a poor conductor.

In contrast, saltwater has a high concentration of dissolved ions (from the salt), which allows it to conduct electricity much more effectively. Copper and aluminum are metals known for their excellent conductivity due to their free-flowing electrons, making them excellent conductors of electricity. Therefore, in this context, distilled water stands out as the least effective at conducting electrical currents compared to the other substances listed.