The apparent narrowing of a river as it flows directly away from you into the distance best illustrates the depth cue known as

A) interposition.
B) closure.
C) relative motion.
D) linear perspective.

Linear perspective is the depth cue that refers to the fact that parallel lines appear to converge as they recede into the distance. This is what causes the apparent narrowing of a river as it flows away from the viewer, making D the correct choice. Interposition refers to the fact that objects closer to us block our view of objects farther away, closure refers to the tendency to perceive incomplete figures as complete, and relative motion refers to how the movement of one object relative to another can indicate depth. None of these cues are specifically related to the apparent narrowing of a river.