If a mirror is placed on the line AB, then which of the answer figures is the right image of the given figure ?

A vertical mirror is placed, so the object on the left will appear right in reverse position and vice-versa.

So the small square (with 2 dots) at top right corner will be reversed and will appear at top left corner, thus the first and third options will be eliminated.

Also, in the question figure, the small circle at bottom left corner is right side of the diagonal, hence it will appear at left side, hence fourth option is the right image.

=> Ans - (D)