How are cliffs formed :D

The sea erodes rocks with hydraulic action and abrasion. More and more erosion occurs making the rock more steeper until it forms a cliff.

Cliff are formed when weathering (snow, ice) and Erosion break down rocks into the cliffs 

Geothermic gradient is the rate of increasing temperature with respect to increasing the depth in the earths interior. away from tech tonic plates boundaries, it is about 25-40 c/km (72-87 degrees f/mi) of depth near the surface in most of the world.

Answer(a); // soil salinization and waterlogging;