The correct answer is - D. fjords.
Fjords are narrow long coastal valleys that were carved out by glaciers. These valleys are usually filled with water from the sea/ocean, and are a very attractive and beautiful natural feature. They are filled with water because once the glaciers melted and the ice age came to an end, the level of the water of the oceans went up, thus flooding the low valleys. The fjords are a trademark of Norway, since they can mostly be found along the coast of this Scandinavian country.
