Which of these is an example of a subsequent boundary? (1) A border separating two states is removed because the states are now one state.
(2) Straight lines or arcs are drawn on a map to show the border between two adjacent countries.
(3) A border is created dividing the North and South of a country because of conflict.
(4) A wall is built along an existing border to keep people from crossing it illegally.
(5) Steep mountains separated two regions before people settled in them.