I need help identifying the three fuel lines on my 2003 Ninja 250?

I have a 2003 Ninja 250. When i take off the seat, there are 3 fuel lines, and the one on the left is cracked. I can't figure out what that line is for. A small amount of fuel vapors come out when i'm running it, but no fuel pours out when i'm running with the tap in any position. What is this line for, and how urgent is it that i get it fixed? Thanks

I need help identifying the three fuel lines on my 2003 Ninja 250?
It's probably a vent line and the three being supply, return, and vent.