Which river flows through London?

The Thames River is the correct answer because it is the primary river that runs through London, serving as an integral part of the city's geography and history. The Thames is significant for its role in trade, transport, and as a cultural landmark, with many iconic structures like the Houses of Parliament and the Tower Bridge located along its banks.

In contrast, the other rivers listed do not flow through London. The Seine River is located in France, flowing through Paris, while the Danube River passes through several countries in Central and Eastern Europe, not reaching the UK. The Nile River is situated in northeastern Africa, primarily in Egypt, and is one of the world's most famous rivers but is far removed from London. Thus, the Thames River is unique in its direct association with the city of London.