If your cross section is from the tip looking toward the handle, I would scrape side B. I remember this confused me for the longest time, and I finally took a bow of mine that I thought was ruined and just experimented with it until I figured it out. The good thing about propeller twists, though, is that since both limbs are twisting in opposite directions, the string usually tracks through the middle of the handle anyway, and you don't have to worry about it.