In ancient Mesopotamia, the Tigris and Euphrates rivers surrounded an area called the "Fertile Crescent." What enduring effect did
these rivers have on trade in ancient Mesopotamia?
A.
They made transportation difficult for ancient Mesopotamians.
B.
They made the Fertile Crescent difficult to reach for trade.
C. They made neighboring areas compete with Mesopotamia.
D. They made transport of agricultural goods economical.