A dilation of a polygon will result in similar shapes, but the points are multiplied by a factor.
In the context of the question, we are given a polygon that needs to be dilated to make the polygon smaller.
Meaning that each x and y coordinate need to be multiplied by a factor that will make the polygon smaller.
A and B won't achieve this as they are adding or subtracting terms from the x and y values, meaning that they will be transformations and not dilations.
C won't achieve this as multiplying the x and y values by a factor of three will result in a larger polygon.
That means your answer is D, because the factor being multiplied is less than 1, the polygon will be dilated about the origin to make a smaller polygon.
Hope this helps!