In a nutshell
Selective Repeat also pipelines a window of frames, but the receiver is smart: it buffers frames that arrive out of order instead of discarding them, and acknowledges each frame individually. So when one frame is lost, only that single frame is resent — the early arrivals are kept and delivered once the gap is filled. Least retransmission of the three ARQ schemes, at the cost of buffering and bookkeeping on both sides.