The correct answer is option 2, Caspian Sea. The Caspian Sea is the largest lake in the world. It is located between Europe and Asia, and it borders several countries including Iran, Russia, and Kazakhstan. The Caspian Sea has a surface area of about 371,000 square kilometers. Lake Superior, option 1, is the largest freshwater lake in the world by surface area, but it is not the largest lake overall. Lake Baikal, option 3, is the deepest and oldest lake in the world, but it is not the largest in terms of surface area. Lake Victoria, option 4, is the largest lake in Africa but it is smaller than the Caspian Sea.