The largest lake in the world by both area and volume is (A) Caspian Sea. The Caspian Sea, although called a "sea," is technically the largest lake on Earth. It is located in Central Asia and is bordered by five countries: Russia, Kazakhstan, Turkmenistan, Iran, and Azerbaijan. The Caspian Sea has significant economic and environmental importance for the surrounding regions and plays a crucial role in the geopolitical landscape of the area.

The Nile can be defined as the longest river by virtue of total head water lenght I.e from where the river is officially called the “Nile". In regard to discharge rate and catchment area the Amazon triumphs the Nile. The Amazon however has a much longer source stream than the Nile.

The sea that does not belong to Russia is (B) Baltic Sea. The Baltic Sea is located in Northern Europe and is bordered by several countries, including Sweden, Finland, Denmark, Germany, Poland, Latvia, Estonia, Lithuania, and Russia. It is not entirely enclosed by Russia. The other seas mentioned (Laptev Sea, Kara Sea, and White Sea) are all located in the Arctic and subarctic regions and are part of the Russian territory.