Which of the following is a true statement about the map?
A. The border between North Dakota and South Dakota is a dashed black line; this indicates a state boundary.
B. The border between North Dakota and South Dakota is a thin, blue line; this indicates a national boundary.
C. The border between North Dakota and Montana is a thin, black line; this indicates a national boundary.
D. The border between North Dakota and Montana is a thick, black line; this indicates a state boundary.
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