A white tile has a diagonal line, a yellow corner triangle, a dot and a small red arrow. Which panel shows the tile as seen in the dashed mirror?

Left and right swap: the diagonal now rises from bottom-right to top-left, the yellow triangle sits in the top-right corner, the dot moves to the bottom-left and the red arrow to the left side, still pointing up: (d). In (b) the triangle has moved but was not flipped, so it no longer fits its corner.