The correct answer is C. People formed government to wage neighboring villages.
This was the main reason which is behind the establishment of government which was done in the early time of river valley civilization.
River valley civilization is termed as civilization or agricultural nation which is situated in a drawing sustenance or besides from a river.
In simple terms civilization is termed as society which has large settlement which is permanent and they feature on urban development, centralized organization, specialization of labour and social stratification.
There are other benefits which come out during the period of river civilization. For example, due to annual flooding there was fertile soil, ease of transportation and fishing.
Egypt and Mesopotamia are the great civilization which grew in river valleys, where by Mesopotamia meant land which was between the rivers.