Which of the following rivers runs entirely within French territory?

The Loire River rises in the southern Massif Central and flowing north and west for 634 miles (1,020 km) to the Atlantic Ocean, which it enters south of the Bretagne (Brittany) peninsula. It drains the widest area (45,000 square miles [117,000 square km]). It is an extremely irregular river, with an outflow eight times greater in December and January than in August and September.

The Loire is artificially joined to the Seine by several canals. The river’s torrential flow, a hindrance to navigation, covers its floodplain with sand and gravel, which has commercial importance. The river is also a source of cooling water for a chain of atomic power stations near its course, which has raised concerns among environmentalists, as have various dam projects along the river.

The Loire Valley has been called the "Garden of France" and is studded with over a thousand châteaux, each with distinct architectural embellishments covering a wide range of variations, from the early medieval to the late Renaissance periods. They were originally created as feudal strongholds, over centuries past, in the strategic divide between southern and northern France; now many are privately owned.