Final answer:
Argentina has declared wine as its national beverage, which is supported by its robust wine industry, particularly in regions like Cuyo and the city of Mendoza.
Step-by-step explanation:
The country that has officially declared wine as its "national beverage" is D. Argentina. This choice is supported by Argentina's significant wine industry, with regions like the Cuyo being central to the country's wine production. In particular, Mendoza within the Cuyo region is renowned for its contribution to Argentina's wine production, accounting for a large portion of the nation's output and highlighting the importance of wine to Argentine culture and economy.