Final answer:
The monocular cue described in the question is Relative Size, which refers to the fact that closer objects cast larger images on the retina than objects farther away. This cue helps us determine the perception of distance.
Step-by-step explanation:
The monocular cue that is described in the question is Relative Size. This cue refers to the fact that closer objects cast larger images on the retina than objects farther away. When an object appears larger, it suggests that it is closer to the viewer. This is a useful depth cue for our perception of distance. For example, if you see a person in the distance that appears much smaller than you, you can infer that they are farther away.