Final answer:
The grape used to make Muscat de Rivesaltes, a sweet fortified wine from France, is the Muscat grape, particularly Muscat à Petits Grains.
Step-by-step explanation:
The grape that is used to make sweet fortified wine named Muscat de Rivesaltes from France is predominantly the Muscat grape, specifically Muscat à Petits Grains. This grape is well-known for producing wines with a rich, sweet profile, which makes it ideal for crafting the luscious, fortified wines of the Rivesaltes region.
Fortified wines like Muscat de Rivesaltes involve halting the fermentation process with the addition of distilled spirits, preserving the natural sweetness of the grapes, which is why Muscat grapes, with their high sugar content and strong aromatic profile, are a perfect choice.