The boundary of the intersection / junction is determined by:

1. The stop lines on each of the roads that meet in the intersection
2. The place in which traffic signs are posted before the intersection
3. Correct answer: The imaginary line drawn between the pavements or kerbs of each road meeting the junction.
4. The meeting of two or more pedestrian crossings in the intersection

WhyA junction is the area between the lines where the roadway edges or kerbs meet, and their imaginary extensions. Signs, crossings and stop lines stand before the junction, not at its boundary.