The correct answer is A. They enriched the soil and helped farmers grow supplies surpluses.
Explanation:
The Tigris and Euphrates are two rivers located in a zone that is called the Fertile Crescent in which the first civilization developed. This can be explained as the existence of this river in this area made the soil rich and therefore it was easier to grow different crops, also the water of the river was used to irrigate crops through canals, which allow people to stay in one area and become a civilization rather than being nomads and created supplies surpluses that made people able to develop a culture and later trade products in land or through the river. Therefore, the role the Tigris and Euphrates river played in the development of civilization is that they enriched the soil and helped farmers grow supplies surpluses.
