1- a is a raised, flat-surfaced area bound on one or more sides by cliffs or steep slopes. a: hill b: plain c: plateau d: river 2- a is the boundary between the land and an ocean or a lake. a: coastline b: dune c: glacier d: hill 3- a is an area of land that rises very high above the land around it. a: lake b: mountain c: plain d: river