Final answer:
The river-valley civilizations developed due to a stable food supply from fertile river valleys, division of labor, the building of cities, writing for communication, and construction of places of worship.
Step-by-step explanation:
The development of the four river-valley civilizations of Mesopotamia, Egypt, the Indus Valley, and China was influenced by several key factors. These civilizations grew along major rivers such as the Nile, Yellow, Tigris, and Indus, which provided rich soil for agriculture and a stable food supply. This abundance allowed populations to become sedentary and grow, leading to the building of villages and cities. As populations increased and remained stable, there was a division of labor that led to people doing different jobs, such as artisans, priests, and rulers. The proximity to a nearby river was crucial because it facilitated intensive agriculture, trade, and transportation. The ability to communicate widely through writing developed over time, enhancing administration, culture, and trade. Lastly, the construction of places of worship became central to these societies, reflecting the spiritual and political significance of religion in daily life and governance.