Answer:
They have no map.
Explanation:
Sailors often used shorelines and islands to help them know their location because they have no map from which they got guidance. For example, an old sailor does not use map for traveling in the ocean due to its experience and some identification or symbols which he remembered that give him information about the way. These identification or symbols must be shorelines and islands because there is no other thing present in the ocean except these so the sailors used these symbols to know their location.
I would say A. Or B hope it helps
