Final answer:
The region known as Mesopotamia is marked on the map as a rectangle at the right end of the Euphrates River in present-day Iraq. Mesopotamia was the cradle of civilization and gave rise to ancient empires like Assyria, Babylon, and Sumer.
Step-by-step explanation:
The region known as Mesopotamia is indicated by the letter on the map that represents the area between the Tigris and Euphrates rivers in present-day Iraq. This region is marked on the map as a rectangle at the right end of the Euphrates River, although the city of Babylon actually occupied both banks of the river. Mesopotamia, meaning 'land between rivers,' was the cradle of civilization and gave rise to ancient empires such as Assyria, Babylon, and Sumer.