The mirror image of an object along the dotted line is

In case of mirror image If mirror is placed right side or vertically then left and right sides of the image will be interchanged in the mirror image.

By visual observation we conclude that option 4 is correct:

• A vertical mirror (dotted line on the right) means left and right positions will interchange, while top and bottom remain the same.
• So:
  • The ‘+’ sign on the top-left shifts to top-right
  • The ‘+’ on bottom-right shifts to bottom-left
  • The filled circle (top-right) shifts to top-left
  • The empty circle (bottom-left) shifts to bottom-right
• The diagonal line also flips direction accordingly.

Only the last option correctly reflects all these changes.