AGRA is seen in the dashed mirror, and that mirror image is then seen in the water below. Which panel shows the final image?

The mirror reverses the word and turns each letter left-to-right; the water then turns everything upside down. Together that is a half-turn: the word reads A R G A from left to right with every letter upside down and reversed, exactly like AGRA rotated half a turn: (d). (b) and (c) stop after one reflection and (a) reverses the order but leaves the letters upright.