Answer: Tigris
Explanation: The Tigris is a river that along with the Euphrates provides fertile soil and water needed for irrigation in Iraq. The importance of these rivers dates back since the formation of the earliest Mesopotamian civilization, which arose from the fertile plain as a result of the geographical position of these two rivers. In today's Iraq, of course, in a different conception of the economy, these two rivers also play an important role in supplying Iraq with irrigation water.