Which of the listed statements describes the reason why oil foaming occurs when starting a refrigeration compressor?

Correct Answer: Option A — This condition is the result of the sudden low-pressure created in the crankcase at start up causing the release of refrigerant absorbed within the oil.

Refrigerant gas is highly soluble in compressor lubricating oil under pressure. When the compressor starts, the sudden drop in crankcase pressure causes dissolved refrigerant to flash and boil out rapidly, creating severe oil foaming and potential lubrication loss.