Correct Answer: (b) Amazon
Solution:Amazon is the longest river in South America. This river is about 6437 km long. Ships can sail up to 1,600 km distance. Apart from this, Nile (6,695 km) of Africa, Mississippi (3779 km) of U.S.A., and the river Ganga (2,525 km) are the important rivers. In terms of length the Nile river is the longest river in the world. Countries like South Sudan, D.R. Congo, Ethiopia, Eritrea, Kenya, Rwanda, Tanzania, Uganda, Burundi, Sudan and Egypt are the part of Drainage basin of the Nile river. Nile river, falls into the Mediterranean Sea.