A 24-hour digital clock is checked at the four times shown. At which of these times does its mirror image read exactly the same as the clock?

In the mirror the characters come in reverse order and each digit is flipped: 2 and 5 swap shapes, 0 and 8 stay. 20:05 reversed is 50:02, and flipping each digit gives 20:05 again. 05:50 becomes 02:20, 08:50 becomes 02:80 and 20:52 becomes 52:05.