This area is known as the Cradle of Civilization? the area surrounding the Caspian Sea

the land between the Mediterranean Sea and the Atlas Mountains

the river valley along the Nile River

the valley between the Euphrates and Tigris Rivers

The valley between the Euphrates and Tigris rivers is known as the Cradle of Civilization.

Explanation:

The first civilizations formed in the river valleys of large rivers and these civilizations are known as river valley civilizations. They emerged in four different regions initially, but the one that is considered to have been the first one emerged in the Middle East. More specifically, the first civilization, Sumer, has developed in the valley of the rivers Tigris and Euphrates.

The term ''Cradle of Civilization'' came to be because it is the place where the first civilization developed. It may seem like a strange place for the development of civilization, but actually provided the basic and most important things for a civilization to emerge. The climate was stable and warm/hot throughout the year, there was always an abundance of freshwater (for the humans, domestic animals, and irrigation), very fertile soil, the rivers also enabled easy transport and travel, and the surrounding deserts provided security from invaders.

answer; (b); i believe its indefinite existence of human population in a healthy and prosperous condition;