Which statement best describes thermal conductivity?

Thermal conductivity is a property of materials that specifically measures their ability to conduct heat. This characteristic is crucial in various applications such as insulation, heat exchangers, and electronics, where efficient heat transfer is often needed. A material with high thermal conductivity allows heat to pass through easily, while a material with low thermal conductivity is more resistant to heat flow, making it a good insulator. The other options relate to different material properties: ductility pertains to a material's ability to deform under tensile stress, strength under pressure refers to a material's ability to withstand compressive forces, and weight concerns the heaviness of a material rather than its thermal properties. Thus, the statement that best encapsulates the concept of thermal conductivity is the one that describes how well a material can conduct heat.