Question

what was the original purpose of the mason - dixon line?
to divide the thirteen original colonies from each other
to demarcate borders for maryland and its neighbors
to limit how close british ships could come to the u.s.

Explanation:

The Mason - Dixon Line was originally surveyed to resolve a border dispute between Maryland, Pennsylvania, and Delaware. It was used to demarcate the borders of Maryland and its neighbors. It had nothing to do with dividing the thirteen original colonies from each other or limiting British ships.

Answer:

to demarcate borders for Maryland and its neighbors