What visual cue helps determine how close or far away objects are based on how they block light?

The visual cue that helps determine how close or far away objects are based on how they block light is shadowing. This phenomenon occurs when an object casts a shadow on a surface, indicating its position relative to the light source and other objects. A deeper or more pronounced shadow typically signifies that the object is closer to the surface, while lighter or less detectable shadows suggest greater distance or variation in light intensity.

Shadowing allows the brain to interpret the spatial arrangement of objects in a way that indicates depth and proximity. For example, when an object casts a distinct shadow, it provides visual information about its size and how close it is to the ground or other items in the scene. The interplay of light and shadow can enhance depth perception by providing cues about the object's three-dimensional form, positioning, and context within its environment.

In contrast, other choices represent different visual cues for depth perception but do not rely on how light is blocked. Motion parallax involves the relative movement of objects as an observer moves, relative height concerns the positioning of objects in relation to a horizon line, and relative size compares the apparent size of objects to infer distance. Shadowing specifically relates to how light impacts our perception of distance among objects through the casting of shadows.