Final answer:
The scenario that best illustrates the use of the size cue for monocular depth perception is when looking at a row of trees, the closer trees appear larger than those farther away.
Step-by-step explanation:
The scenario that best illustrates the use of the size cue for monocular depth perception is B) When looking at a row of trees, the closer trees appear larger than those farther away.
This is an example of relative size, which is a monocular depth cue. When objects are at different distances from us, smaller objects generally appear farther away, while larger objects appear closer.