A lock-gate shows the number 6093 above the canal water. Which panel shows the number reflected in the canal?

The digits stay in the order 6 0 9 3 and each is flipped top-to-bottom: 0 and 3 do not change, the 6 gets its loop at the top with its long side on the LEFT (a backward 9, not a 9), and the 9 gets its loop at the bottom: (b). (d) turns each digit left-to-right, (a) reverses the number and (c) is a half-turn.