Final answer:
Access to fertile land for agriculture was a necessary condition for the development of ancient river civilizations, enabling a food surplus and stable, settled communities that laid the groundwork for the growth of civilization.
Step-by-step explanation:
The statement that describes a necessary condition for ancient river civilizations to develop is access to fertile land for agriculture. Ancient societies such as those in Egypt, Mesopotamia, and China settled along major river valleys like the Nile, the Yellow River, and the Tigris to utilize the rich, fertile soil for agrarian purposes.
This fertile land provided a food surplus which allowed for population growth and the formation of stable, settled communities.
These primary conditions of agriculture led to the development of a discernible culture, supported specialized occupations, and ultimately facilitated the rise of civilizations.
Over time, as ruling classes and wealth increased, so did the demand for technological advances, strong centralized government, and abundance of natural resources, which would further shape these societies.