Concept:A river basin is the area drained by a main river and its tributaries. The largest river basin in the world is measured by area.Explanation:The Amazon River basin covers over 7 million square kilometers.It stretches across almost half of South America, including eight countries.Compare its size with other major basins:
River basin
Area (km^{2})
Ganga river basin
0.8 M Km2
Nile river basin
3.4 M Km^{2}
Mississippi river basin
3.22 M Km2
Amazon river basin
7M Km2
The Amazon basin is clearly the largest among the given options.
