Answer:
Caspian Sea, is the right answer.
Explanation:
The longest of all rivers in Europe is the Volga river. The area of this river is around 1,350,000 square Km. In terms of drainage basin and discharge, this river holds the first place. This river is known as Russia's national river, the course of this river covers central Russia and into the Caspian Sea. This river is associated with Caspian Sea's closed basin.
