5. Piece of land surrounded by water on all four sides is called an island

the correct answer is 2.

a slump in geology means a mass movement process of slope failure. a mass of rock or unconsolidated material drops along a slip surface. in other words, rock layers move a short distance down the slope. the slump block is an intact block (2), without any landslide material.

in this image, 1 is the surface of rapture (scarp), 2 the slump block, 3 main scarp (crown), 4 base of rapture with debris flow.

slumps are caused by clear cutting on unstable soils and the sagging of earth, in coastal areas they are due to wave infiltration.