What is the function of the oil control ring (typically the bottom-most ring assembly) on a four-stroke motorcycle piston?

1. To scrape excess lubricating oil off the cylinder wall and return it to the oil sump, preventing it from entering the combustion chamber.
2. To seal the high combustion pressures inside the cylinder and prevent blow-by.
3. To transfer heat from the piston crown directly to the cylinder cooling fins.
4. To spray oil upward toward the piston pin to lubricate the small end of the connecting rod.