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

Correct — A.

The figure is the string HfC632a, and MN is the vertical line standing to its right. A mirror on a vertical line gives a left-to-right flip.

Rule: reverse the order of the characters, and reverse each character in place. Nothing moves up or down.

Reversed order: a, 2, 3, 6, c, f, H. Each glyph is then turned back to front — H is unchanged, because H is symmetrical about a vertical axis, and the other six are not.

Option (a) does exactly that. Hold it against a vertical mirror and HfC632a reads back in its printed form → option (a).

Why the others are wrong

• (b)
  This is the string turned through 180°, not reflected. A half turn flips top-to-bottom as well as left-to-right, so its characters stand on their heads instead of merely facing the other way.
• (c)
  The order is reversed and almost every glyph is turned, but the C still opens to the right, exactly as in the original. In a vertical mirror that C has to open the other way.
• (d)
  It leaves a, 3 and 2 upright at the left-hand end while reversing H, f, C and 6. A reflection turns every character; it cannot turn some and leave the rest alone.

When the mirror line MN is drawn beside a figure it is vertical, and the image is the plain left-to-right flip. Two things happen at once: the order of the characters reverses, and each character is reversed where it stands.

Characters with a vertical axis of symmetry come through unchanged. Among capitals those are A, H, I, M, O, T, U, V, W, X and Y, which is why the H at the end of the mirror image still reads as an H.

The other six glyphs here have no vertical axis. C is symmetric about a horizontal axis, not a vertical one, so f, C, a, 6, 3 and 2 all have to change, and that is where the four options differ.

Key facts

• The mirror line MN here is vertical and stands to the right of the string, so the image is a left-to-right flip.
• A vertical mirror reverses the order of the characters and reverses each character in place.
• Capitals with a vertical axis of symmetry, such as A, H, I, M, O, T, U, V, W, X and Y, look unchanged in such a mirror.
• A 180 degree rotation also reverses the order of the characters, which is why it can be mistaken for a mirror image.

Common traps

• Reversing the order of the characters but leaving each one facing its original way.
• Picking the 180 degree rotation, which looks reversed at a glance but is upside down.
• Deciding on the first two glyphs when the options differ in only one character.

No directly related past PYQ was found.