Answer:
d.
Step-by-step explanation:
For a point on a non-degenerate conic, we have distances, such as the distance to the center, to the directrix, to the focus, or to the vertex.
Now, in this case of a non-degenerate conic, there can be two distances that serve keep a constant relationship due to its geometry and it is:
d. distance to focus: distance to directrix
