Select the correct mirror image of the given alphanumeric string when a vertical mirror is placed to its right at $MN$, as shown below:

When a mirror is placed vertically on the right side ($MN$):
1. Reversal of Order: The left-to-right sequence of the characters is completely reversed. The rightmost character appears first in the mirror image, and the leftmost character appears last.

$$\text{Original Sequence: L}\to 2\to 7\to \text{A}\to \text{e}\to \text{f}$$

$$\text{Mirror Image Sequence: f}\to \text{e}\to \text{A}\to 7\to 2\to \text{L}$$

2. Lateral Inversion: Each individual character is flipped horizontally:
* f becomes its horizontally inverted form (hook pointing to the top-left).
* e becomes $\text{ɘ}$.
* A remains unchanged ($\text{A}$) due to vertical symmetry.
* 7 becomes $\text{𝚪}$.
* 2 becomes $\text{Ƨ}$.
* L becomes $\text{⅃}$.

Evaluating the Options:

* Option A: The digits '2' and '7' are not inverted. (Incorrect)
* Option C: The characters are vertically inverted, forming a water image. (Incorrect)
* Option D: The letter 'A' is inverted vertically ($\text{∀}$). (Incorrect)
* Option B: All characters are correctly flipped horizontally and arranged in the correct reversed order. (Correct)