Final answer:
The Dniester and Tigris rivers derive their names from the Sarmatian language, with the Tigris being the correct answer as it shares the first four letters and is located in Mesopotamia.
Step-by-step explanation:
The rivers Dniester and Tigris are both said to get their names from the Sarmatian language, suggesting that the correct answer to the question is the Tigris River. The Dniester flows through Ukraine and Moldova, while the Tigris is one of the most historically significant rivers in Western Asia. Together with the Euphrates, the Tigris River defines the region known as Mesopotamia, which is situated between these two rivers now in parts of Syria, Turkey, and Iraq.