The correct option is D.
Metals have different properties which are utilized in diverse ways to meet the need of man. One of the properties of metals is thermal conductivity. Thermal conductivity refers to the ability of the metal to conduct heat. This property is especially useful in the working of electric pressing iron. The heat released by the metal that is used in the manufacturing of the iron is regulated by mean of thermostat, which keep the heat constant in order to protect the clothes been ironed from damage.