A conductor is best described as what?

A conductor is best described as a medium that allows heat, electricity, or light to pass through it. This definition encompasses the properties of conductors in both thermal and electrical contexts. For instance, metals like copper and aluminum are excellent electrical conductors because they allow electrical current to flow easily through them. Similarly, certain materials can also conduct heat efficiently, which is why metals are often used in cookware and radiators. Light conductors are less common but can include materials like fiber optics that transmit light signals effectively.

The other options do not align with the characteristics of conductors. A substance that prevents heat movement refers more accurately to insulators, which resist heat flow. Non-metal substances can vary widely; while some non-metals can be conductors (like graphite), they are not predominantly known for conducting electricity or heat. Lastly, sound insulation refers to materials that can impede sound transmission, again fundamentally different from the characteristics of a conductor. Overall, option B captures the essence of what a conductor is across multiple domains while other options mischaracterize its fundamental properties.