Sub cooling is best described as the amount of heat that is _________.

Subcooling refers to the process of removing heat from a refrigerant after it has transitioned from a vapor to a liquid state during condensation. The correct answer highlights that subcooling specifically deals with the cooling of the refrigerant below its saturation temperature after it has fully condensed. This additional cooling enhances the efficiency of the cooling cycle and ensures that the refrigerant is completely in liquid form when it is sent back to the evaporator.

In practical applications, achieving effective subcooling can help prevent the refrigerant from entering the evaporator in a partially vaporized state, which can lead to reduced system efficiency and potential damage. Therefore, understanding this process is critical for optimizing refrigeration and air conditioning systems.