Originally Posted by BV

2 small lines are hot and cold cpvc supply lines

large one is sewer drain pvc, unscrew it and take whiff ;-)

definitely was for a utility sink based on the height from the floor

a washer would have been much higher, however you could raise the sewer line and install a p trap (so sewer gas does not escape) the sink that was there had the p trap under the drain of the sink basin. you also would want to raise the supply lines so you don't have to reach behind to turn off the water) if you want to install a washer there

definitely not anything to do with a natural gas or propane line as others have suggested