Because of the three rules, I entered WGR from the bottom up in boxes 1,2,3 and assumed that another red would have had to go in 4,5,6. which made me choose the B answer choice, but that’s incorrect, because two reds could’ve went above 3.
What led you astray was the assumption that the first 3 boxes must be WGR. For instance, they could be GWG. As long as there’s any WB block, the last rule will be satisfied, and as long as there are no reds below the lowest green, the second rule will be satisfied. Don’t want to give away the whole thing just yet, but play around with it with that information, and if you’re still stuck on it, re-post & I’ll solve.