Fruit tree

This is either my grapefruit or lemon tree. Not sure which one it is. We got 3 fruit trees last year; lemon, lime and grapefruit. One of them didn't make it through that day of winter we had. Since there was never any fruit on these trees, I don't remember which one this is. The one that had some fruit last year was a lime tree and I believe this is not that one. Oh well, it's just going to be a surprise then.