A square board is changed from A to B. The same change is made to C. Choose the correct answer figure.

From A to B the board is reflected in its slanting line from the top-left corner to the bottom-right corner: the orange square goes from top-right to bottom-left, the triangle from bottom-left to top-right and its point turns from right to down. Reflecting C in the same line moves the dot to the bottom-left, keeps the flag and the yellow square on the line, and swings the flag so its pole lies flat pointing left: (c). (b) uses the other diagonal and (a) an upright mirror.