Which one among the following rivers is the longest?

1. The length of a river can be measured in various ways, but based on generally accepted figures, the Amazon River in South America is considered one of the two longest rivers in the world, often cited as slightly shorter or slightly longer than the Nile, depending on the measurement source and method (around 6,400 km to 6,992 km). 2. The Amur River (Asia) is approximately 2,824 km long (or longer if considering its source tributaries). 3. The Congo River (Africa) is the world's deepest river and the second-largest by discharge volume, with a length of about 4,700 km. 4. The Lena River (Russia) is about 4,294 km long. 5. Comparing these lengths, the Amazon is the longest among the options provided.