What is true of sand dunes found at the beach? A) They are built by waves
B) They are made by rivers cutting through land
C) They are built by water carrying sediment away
D) They are built by the deposition of sand by wind

D.

Explanation:

I have said this before, so, Coastal dunes form when the wet sand is deposited along the coast and dries out, and is blown by wind along the beach! The  Dunes form where the beach is wide enough to allow enough of wind-blown sand, and where prevailing onshore winds tend to blow a sand island! I hope this helped!

yes, post it and i can try to you out.