Final answer:
The land between the Tigris and Euphrates rivers is known as the Fertile Crescent, a region important for the development of ancient civilizations.
Step-by-step explanation:
The land between the Tigris and Euphrates rivers, where civilization first began, is known as b) the Fertile Crescent. This region, often referred to as the Cradle of Civilization, hosted some of the earliest complex urban centers in ancient Mesopotamia. The Fertile Crescent's rich agricultural valleys encouraged the development of civilization as far back as the fourth millennium BCE. Today, this area corresponds to parts of modern nations such as Egypt, Iran, Syria, Jordan, Israel, Lebanon, Turkey, among others. The region was ideal for the emergence of human civilization owing to its climate, fertile soils, and the availability of fresh water from the Tigris and Euphrates Rivers.