Option 1 (on) -> Used for surfaces or when something is located along a street, but not appropriate for junctions.
Option 2 (at) -> Used for specific points or locations like junctions, intersections, and precise addresses.
Option 3 (over) -> Indicates a position above something, which doesn't fit the context of a junction.
Option 4 (in) -> Used for enclosed spaces or larger areas, not for specific points like junctions.
Hence, Option 2: at -> "At" is the correct preposition to use with "junction" because a junction represents a specific point or location where roads meet, and "at" is used to indicate precise positions or points -> correct