If a technician checks a new piston ring's end gap inside a cylinder bore and finds it is below the manufacturer's minimum specification, what corrective action must be taken?

1. Install the ring as is, as it will wear down quickly during engine break-in.
2. Use a piston ring end-gap filer to carefully file material from the tips of the ring until the gap meets specifications.
3. Hammer the piston ring to stretch it.
4. Bore the cylinder larger until the gap matches.