Which of the following is a true statement about the map? a. the border between canada and north dakota is a thick, black line; this indicates an international boundary. b. the border between montana and north dakota is a thin, black line, this indicates an international boundary. c. the border between montana and north dakota is a thin, blue line; this indicates a state boundary. d. the border between canada and north dakota is a thin, black line; this indicates an international boundary.