To solve the problem of identifying the correct mirror image of the given figure when the mirror is placed at line MN, follow these steps:

1. Understand Mirror Reflection: When a mirror is placed vertically to the right of a figure, the mirror image will reflect each element of the figure, reversing the order horizontally.
2. Identify Element Placement: In the given image, the order of elements from left to right is: g, h, i, !, c, 7, L, d. The mirror is placed on the right (at MN).
3. Reverse the Order: The mirror image will reverse the order of these elements. The order in the mirror image from left to right will be: d, L, 7, c, !, i, h, g.
4. Visualize Individual Elements: Observe how certain characters and symbols appear in a mirror:
   • The characters 'd', 'L', '7', 'c', '!' will appear flipped horizontally.
   • The characters 'g', 'h', 'i' will also appear reversed.
5. Compare Options: Compare the reversed order and appearance with the provided options to determine the correct mirror image.

After examining the images provided as options, the correct mirror image is the one that follows the sequence and appearance outlined above.

This option correctly displays the mirror image with the mirrored sequence: d, L, 7, c, !, i, h, g.