Final answer:
The transformation rule (x,y) —> (cx,cy) is a dilation.
Step-by-step explanation:
The description that goes with the transformation rule (x,y) —> (cx,cy) is C. Dilation. Dilation is a transformation that changes the size of an object without changing its shape. In this transformation, both the x-coordinate and y-coordinate are multiplied by the scale factor c, resulting in the object being stretched or shrunk.