Answer:
Step-by-step explanation:
Coastlines are continually eroded by longshore currents.
Longshore currents are ocean currents that flow parallel to the shoreline. They are created when waves approach the shore at an angle, and the water is deflected by the friction of the bottom and the shape of the coastline. The resulting current flows parallel to the shore, and can cause erosion of the coastline over time.
Parallel shore currents and shortshore currents are not correct terms. Perpendicular shore currents are not a natural phenomenon and do not occur in the real world.