When can vapor be condensed at a high temperature?

The correct choice highlights that vapor can be condensed at a high temperature when the pressure is sufficiently elevated. In thermodynamics, the relationship between pressure and temperature in the context of phase changes is encapsulated in the principles outlined by the refrigerant's saturation curve.

As pressure increases, the saturation temperature also rises, meaning that at higher pressures, the vapor requires a higher temperature to remain in a gaseous state. Therefore, when a vapor is subjected to high pressure, it can reach higher temperatures before transitioning into a liquid state. This principle is instrumental in refrigeration cycles, where controlling pressure allows operators to manipulate the condensation process efficiently.

Understanding that condensation occurs due to the temperature and pressure interplay is crucial for refrigeration operators since it affects the efficiency and performance of the refrigeration systems they manage.