Which mathematical relationship best describes a graph of gravitational field strength versus distance? 
(one of the 3 pictures attached or none of the above?)

Which mathematical relationship best describes a graph of gravitational field strength versus distance one of the 3 pictures attached or none of the above class=
Which mathematical relationship best describes a graph of gravitational field strength versus distance one of the 3 pictures attached or none of the above class=
Which mathematical relationship best describes a graph of gravitational field strength versus distance one of the 3 pictures attached or none of the above class=