Final answer:
The temperature of the kitchen increases when the refrigerator door is left open due to the heat expelled by the refrigerator's cooling system and the motor's work, which both contribute to a warmer ambient temperature.
Step-by-step explanation:
If the refrigerator door is left open, the temperature of the kitchen is likely to increase. This is because refrigerators are designed to remove heat from the inside and expel it to the surroundings.
When the door is open, the refrigerator's cooling system continues to run, resulting in continuous work to transfer heat from the inside to the already-room-temperature air of the kitchen. This process adds heat to the kitchen, thereby increasing the ambient temperature slightly.
Additionally, there is a conservation of energy principle at play, which means that the work the refrigerator's motor does will be ultimately converted into heat, contributing further to the rise in temperature.
Therefore, the correct answer to the question is: (a) Increases.
It is important to note that while this effect may be relatively small and the kitchen's temperature change might not be drastic, the refrigerator will have to work harder to remove increased amounts of warm air continuously, which can lead to higher energy consumption and inefficiency.
It's a common misconception that one could cool a room by leaving the fridge door open, but this action actually results in the opposite effect due to the heat expelled by the fridge's condenser.