Two monocular depth cues are most responsible for our ability to know that a jet flying overhead is at an elevation of several miles. One cue is relative size. What is the other? a. Relative motion. b. Retinal disparity. c. Interposition. d. Light and shadow. e. Linear perspective.

Answer: Relative motion

Explanation: Relative motion can be defined as the change of position with respect to time of an object as observed from a particular reference frame, and it varies with the choice of reference frame. The motion is not calculated with reference to the earth, but is calculated with reference to the velocity of the object in the reference frame.