How does the river contribute to one of the theories of landform development?

Geomorphic cycle of the landscape development or the cycle of the erosion.

Explanation:

The geomorphic cycle is a cycle of erosion that was given the famous geomorphologist William morris Davis in the year 1884, as he stated that the landforms are changes by the river stages of the youth and the mature n the olde stages. The landforms grow slowly were as the work of the river as fast as it reduced the terrain form the above. Into a  low featureless plain called the peneplain and it applies to the landforms that are formed by the hills, the valleys ad the drainage systems.

The answer is a but it also might be 7 so

The enviroment with hedge hogs