A transparent square sheet carries the pattern shown. It is folded along the dotted diagonal so that the top-right half falls onto the bottom-left half. Which figure shows what you see on the folded sheet?

Folding on this diagonal mirrors every mark of the top-right half in it, which swaps each point's across and down distances: the L along the top and right edges lands along the left and bottom edges, and the dot at 6 across, 2 down moves to 2 across, 6 down. The slanting line stays where it is: (b).