The term 'oil foaming' in refrigeration practice, is used to describe what event?

Correct Answer: Option A — release of miscible refrigerant from the lubricant in the crankcase

Crankcase oil foaming occurs when system pressure drops rapidly, causing refrigerant miscible in the compressor lubricating oil to boil out violently from solution. This creates foam that can strip lubricated bearings and cause liquid slugging.