The spread of the Spanish language across southwestern portions of the United States is an example of
a. cultural diffusion.
b. culture region.
c. linguistics.
d. economic activity.
It is not an economic activity - it's linguistic in nature, not economic.
It is not linguistics either - linguistics is a scientific discipline.
It's also not a culture region - this would be a kind of region, and a region is not the same as spread of culture. The correct answer is "a) cultural diffusion.
