Correct Answer: (a) Splash erosion, Sheet erosion, Rill erosion, Gully erosion
Solution:The correct order of soil erosion process is splash erosion, sheet erosion, rill erosion and gully erosion. Splash occurs when the raindrop hits the surface; explosive impact soil into individual particles. Sheet erosion is the detachment of soil particles by rain drop and their removal down slope by water flowing overland as a sheet in definite channels. Rill erosion refers to the development of small ephemeral concentrated flow paths which function as both sedimentary source and sediment delivery systems for erosion on hill slopes. Sheet erosion removes the this top layer by raindrop kill or orion occurs in lines which are less than 30 cm deep when these rills are deeper than 30 forming channels are called as gully erosion. Gully erosion occurs when water flows in narrow channels after heavy rain and melting snow.