The Volga river is the largest river in Europe, so that should be the answer.
Answer: B. It is useful for navigation.
Explanation:
The Mercator is a famous map projections that was created by Geradus Mercator who was a Flemish geographer in 1569.
The Mercator is used for nautical purposes and is regarded as the standard map projection due to the fact that the lines of true direction can be represented on it and hence useful for navigation.
The most appropriate answer would be magma. Lava is a magma that reaches the Earth's surface, which is technically it is also a magma, and magma is located below the Earth's surface.
Lava at Earth's surface or magma below Earth's surface cools and harden to form mineral crystals.
St. John's is the capital of Antigua and Barbuda