Where to blow out line (picture)

[Charrua2]

I was hoping to close my own pool and the one thing I can't figure out is where to connect the air compressor in order to blow out the lines. From what I can see, I only have two openings where it can be connected (see picture). The PVC connections are all glued everywhere else. So do I connect to A (opening to filter basket) or B (opening to backwash hose), or none of the above? I also assume that I should change the filter to "winterize" when blowing out the lines. Please confirm. Thank you.