Which of the following would be an example of cultural diffusion?
a. the spread of a language, such as 28 spreading across the u. s.
b. preservation of traditional values
c. preservation of modern values
d. the difference between regional dialects

Cultural diffusion means that some cultures and values would spread from one place to another. So it's not enough for them to be preserved in the original place, (this makes us exclude options B and C)  but they need to be spread to other places, such as to other parts of the US - the correct answer is a)