When reflecting a point over the line [tex]\( y = x \)[/tex], the coordinates of the point are swapped. This means that the [tex]\(x\)[/tex]-coordinate and the [tex]\(y\)[/tex]-coordinate exchange places.
Given the coordinates of point [tex]\( D \)[/tex] as [tex]\( (a, b) \)[/tex], after reflecting over the line [tex]\( y = x \)[/tex] we switch the coordinates [tex]\( a \)[/tex] and [tex]\( b \)[/tex].
Therefore, the new coordinates of point [tex]\( D' \)[/tex] (the image of [tex]\( D \)[/tex]) will be [tex]\( (b, a) \)[/tex].
Thus, the correct answer is:
[tex]\[ (b, a) \][/tex]
