Which of the following is a true statement about the map?
A. The border between Canada and the United States is a thin, blue line; this indicates a national boundary.
B. The border between Mexico and Texas is a thick, Black line; this indicates a national boundary.
C. The border between Mississippi and Arkansas is a thin, black line; this indicates a national boundary.
D. The border between Mississippi and Arkansas is a thin, blue line; this indicates a natural river boundary.