[I am planning to finish my basement. When I bought the house they said it is roughed in for a full bathroom, but I'm unable to figure out what the drain pipes are.
My guess is the right one is for sink, center one if for toilet and the left one is for shower but the drain seems to be very large for a shower.
Edit: I added a clearer picture with all the drains. My understanding so far is the 2" inch line is vanity drain, 4" inch line is toilet drain, 5 gal bucket is the shower drain. The 2" inch drain goes inside the wall. One thing I am unable to figure out is the vent, I don't see any vent lines in the basement, everything seems to be a drain pipe.