The correct answer is C. The formation of permanent settlements.
Step-by-step explanation
The Neolithic revolution refers to the period of time that implied changes in society that made agriculture the main economic activity of human groups. Among these changes, one of the most important was the end of nomadism, because during this revolution human communities stopped moving and instead settle in a single place to live, build homes and grew plants to meet their basic needs. Many of these communities develop next to rivers, including the River Valley Civilization. Many of these communities develop next to rivers, including many of the river valley civilizations such as Mesopotamia or Ancient Egypt because living near to the river allowed people to have constant access to a source of water for their needs, and also this made the soil fertile for agricultural activity. So, the correct answer is C. The formation of permanent settlements.