Which is one way that the neolithic revolution contributed to the development of ancient river valley civilizations?

The Neolithic Revolution, also called the Agrarian Revolution, was the change from a nomadic, hunter-gatherer lifestyle to a settled, agrarian one with farming. Farming is more stable and secure and it gives people more time to engage in other activities, such as improving their tools and developing cultures: the neolithic Revolution contributed to the technological development in the river valley civilisations by giving people time to improve on their technology.

I'm pretty sure that's called a volcano