Final answer:
The phenomenon where railroad tracks appear to converge in the distance is called linear perspective, a monocular depth perception cue that creates the illusion of depth as parallel lines recede towards a vanishing point.
Step-by-step explanation:
Railroad tracks appear to converge in the distance due to a depth perception cue known as linear perspective. This is an optical illusion where parallel lines seem to come closer together or converge as they recede into the distance. In the context of railroad tracks, as the tracks get farther away from the viewer, they appear to be getting closer to each other until they meet at what is called the vanishing point on the horizon.
Another depth perception cue mentioned in this context is orthogonals, which are the lines that follow the technique of linear perspective, converging at the vanishing point to create the illusion of depth on a two-dimensional plane. It is a powerful monocular cue, which allows for the perception of depth with just one eye. Linear perspective can be observed in various scenarios such as in the streets, buildings, or any situation where parallel lines exist and extend into the distance.
The correct answer to the question is b) linear perspective.