The correct answer is - the United States.
With the victory in the Spanish-American War, the United States managed to promote themselves as an imperial power, and also as a country that is strong, is on the rise, and should be well respected and feared.
The United States managed to gain a lot of new territory, Texas, New Mexico, Arizona, Nevada, California, Utah, as well as the entirety of Colorado, Wyoming, and Kansas. This increased the territory of the United States by far, it managed to become the dominant power in the region, it gained much more coastline on the Pacific, as well as on the Gulf of Mexico. Lot of natural resources were also gained as these territories are rich in numerous natural resources, an that helped to boost the economy and development even further.
