Of the listed materials, which is the poorest conductor of electricity?

Slate is indeed the poorest conductor of electricity among the listed materials. It is a type of metamorphic rock that is primarily used in construction and roofing due to its insulating properties. Its molecular structure does not allow for the easy flow of electricity, which is why it is categorized as a poor conductor.

In contrast, copper, iron, and aluminum are all metals known for their conductivity. Copper is one of the best electrical conductors and is widely used in electrical wiring due to its excellent conductivity and resistance to corrosion. Aluminum, while not as conductive as copper, is still a good conductor and is often used in power distribution and overhead power lines due to its lighter weight and lower cost. Iron, while not as effective as copper or aluminum, is better at conducting electricity than slate. Thus, slate’s nature as a non-metallic and insulating material makes it the correct answer in this context.