Choose the correc A. Proximity to the sea

B. Plain region

C. Availability of water

D. Climate

Human settlements refer to the organised and structured human habitation in different regions. The concentration of settlement depends upon many important factors like the availability of water, natural resources, climatic conditions and the type of region. Even though the nature of the region and the climatic conditions also influence the concentration of settlement, the availability of clean water is the most important determinant. Because of this reason, we can find most of the ancient human habitation on the banks of the rivers. Thus the availability of water is the most important determinant of the concentration of human settlement.