To determine the correct mirror image of the given figure when the mirror is placed at MN, we need to visualize how each character in the sequence will appear when reflected.

In a mirror image, characters are reversed horizontally. This means the leftmost character appears on the rightmost side and vice versa. Additionally, any characters that are not symmetrical (like the letter 'R') will face the opposite direction.

Let's analyze how the given sequence RF5mGYus would transform:

• R transforms to a reverse image of 'R'.
• F transforms to a reverse image of 'F'.
• 5 is symmetrical and would appear as '5'.
• m is symmetrical and would appear as 'm'.
• G transforms to a reverse image of 'G'.
• Y is symmetrical vertically, but its orientation will make it appear different.
• u transforms to a reverse image of 'u'.
• s transforms to a reverse image of 's'.

Now placing these characters in reverse order:

s u Y G m 5 F R

Checking each option, we find that the option that correctly displays this transformation is: