Select the correct mirror image of the given figure when the mirror is placed at MN as shown below.

Correct — D. MN is a vertical line to the right of the string, so the reflection is a lateral inversion: the order of the characters reverses and each character is flipped left to right.

Reversing 5 n E r 6 3 A gives A 3 6 r E n 5.

Now flip each one. A is symmetric about a vertical axis and the lowercase n as printed here is too, so both look unchanged. The 3, 6, r, E and 5 all turn backwards.

Option (d) shows precisely that sequence.

Why the others are wrong

• (a)
  It prints 6 and 3 in their original order and the right way round. A mirror reverses the sequence and each glyph, so those two digits must swap places and turn backwards.
• (b)
  Its A is turned upside down. A vertical mirror leaves A alone, and flipping a character top to bottom is a water image, not the mirror image at MN.
• (c)
  Its final character is an ordinary 5. The 5 has no vertical axis of symmetry, so it has to appear reversed like the other asymmetric characters.

A mirror on a vertical line produces lateral inversion, and two things happen at once. Candidates usually do one of them and stop.

First, the sequence reverses. What stood nearest the mirror still stands nearest it, so the rightmost character of the string becomes the leftmost of the image.

Second, each character is reflected in itself. Characters with a vertical axis of symmetry, such as A, H, I, M, O, T, U, V, W, X and Y, come through unchanged, and everything else turns backwards.

Digits behave the same way: 0 and 8 survive a vertical mirror, while 2, 3, 5, 6, 7 and 9 do not.

Key facts

• A vertical mirror reverses the order of the characters and reflects each character.
• Reversing 5 n E r 6 3 A gives A 3 6 r E n 5 before any glyph is flipped.
• A, H, I, M, O, T, U, V, W, X and Y are unchanged by a vertical mirror.
• A top-to-bottom flip is a water image, which is a different question from the one asked at MN.

Common traps

• Reversing the order but leaving the characters themselves unflipped, as option (a) does
• Flipping a symmetric character anyway, as option (b) does to the A
• Missing the last character of a long string, as option (c) does with the 5

No directly related past PYQ was found.