A fjord coastline consists of U shaped, formerly glaciated valleys, leading down to the coastline that have become flooded due to sea level rise since the end of the last ice age. They are generally quite broad and deep and act as natural harbours. The illustration that best shows this is A.

B shows a longitudinal coastline where the flooded valleys parallel the coastline.

C shows an estuarine delta.

D shows a ria coastline with drowned V shaped, non-glaciated valleys.