The answer is E. Niagara.
The other four rivers are all in Africa. The Volga is in Russia, the Nile is in Egypt, the Amazon is in South America, and the Congo is in Central Africa. The Niagara River is on the border between the United States and Canada.
The Volga is the longest river in Europe, flowing 2,292 miles (3,689 km) from Valdai Hills in Russia to the Caspian Sea. The Nile is the longest river in the world, flowing 4,132 miles (6,650 km) from Lake Victoria in Uganda to the Mediterranean Sea. The Amazon is the largest river by discharge, flowing 4,000 miles (6,400 km) from the Andes Mountains in Peru to the Atlantic Ocean. The Congo is the second-largest river in Africa by discharge, flowing 2,920 miles (4,700 km) from the highlands of East Africa to the Atlantic Ocean. The Niagara River is a major river in North America, flowing 36 miles (58 km) from Lake Erie to Lake Ontario. It is famous for its waterfalls, which are the largest waterfalls in North America.