Fact 1: Erosion causes a river to become deeper and wider.

Fact 2: Fertile topsoil is then lost in erosion.

Given the two facts above, answer the question "Deepening rivers cause" with the following options: 
- relocation
 - the loss of topsoil
 - Plant growth is reduced
 - to move people
 - Physical weathering
 - forest is destroyed
 - Water expanding
 - water conservation


 

  the loss of topsoil       