The Fertile Crescent has been called the crossroads of the world because it was A. The first center of advanced civilization

B. Often flooded by the Tigris and Euphrates Rivers

C. Protected from invasion by the surrounding deserts and mountains

D. On the trade routes connecting Europe, Asia, and Africa

D.  On the trade routes connecting Europe, Asia, and Africa

Explanation:

The Fertile Crescent was widely known as the cradle of civilization. However, it is also known as "Crossroads" because the territory covers a large expanse of lands which spans across three continents, including present Africa, Europe, and Asia. Some of the countries are Egypt, Iraq, Israel, Palestine, Turkey, Jordan, etc.

Hence, the correct answer is option D. On the trade routes connecting Europe, Asia, and Africa