The correct option is B
Perennial rivers have an uninterrupted flow of water throughout the year, regardless of the season, although some perennial rivers may stop flowing during a severe drought. The perennial rivers drain a large area that forms the river basin, such as the Amazon River, which covers an area of 2.7 million square miles and is the largest basin in the world. The Congo River in Africa drains an area of 1.5 million square miles, making it the second largest river basin in the world.