Final answer:
The correct answer is a) Nile. People discovered fertile soil and predictable annual flooding in the Nile valley, which were essential for their settlement and agriculture. The Nile's reliable flooding patterns allowed for the establishment of prosperous agricultural villages and the advancement of ancient Egyptian civilization.
Step-by-step explanation:
When people first began moving into the Nile valley, they discovered a rich and fertile region, ideal for agriculture. This area along the Nile from the Mediterranean to northern Sudan showed evidence of flourishing agricultural villages by 4000 BCE, engaged in trade and the development of sophisticated irrigation networks. The Nile River was crucial to the growth of these settlements because its predictable flooding provided nutrient-rich soil convenient for planting, enabling ancient Egyptian civilization to thrive. Ancient Egyptians benefitted from the river’s seasonal flooding, which deposited nutrients onto their farmlands, supporting plentiful harvests and the creation of urban societies with a surplus of crops.
Unlike the unpredictable Tigris and Euphrates rivers, the Nile's predictable flooding patterns allowed for the planning and development of efficient agricultural systems. The Nile River valley and its success in farming and centralized government contrasted significantly with other regions, such as those near the Congo River, mostly due to the different environmental challenges and societal responses to those challenges. Overall, the Nile's reliable annual flooding was a cornerstone for the successful and sustained development of the ancient Egyptian civilization.