Q. Which one among the following rivers is the longest? (UPSC Prelims 2007)
Answer: Amazon
Notes: The Amazon River is the world's longest, measuring approximately 6,575 to 7,000 km. It flows through South America from the Andes to the Atlantic Ocean. The Lena (4,400 km), Amur (4,444 km), and Congo (4,700 km) rivers are all shorter. This geographical data confirms that the Amazon is longer than the other rivers listed.