18. One reason for the development of an early civilization in the Tigris-Euphrates river valleys was that A) the location protected the people from land invasion B) these rivers flowed into the Mediterranean Sea C) periodic flooding left rich soil, which was ideal for farming D) these rivers provided a direct trade route between Europe and Asia

18. One reason for the development of an early civilization in the Tigris-Euphrates river valleys was that A) the location protected the people from land invasion B) these rivers flowed into the Mediterranean Sea C) periodic flooding left rich soil, which was ideal for farming D) these rivers provided a direct trade route between Europe and Asia