Hey there, while I do know the answer to this because it's in my notes, I apologize if it isn't what you happen to be looking for.
Which term is used to describe the spread of Buddhism from India through Southeast Asia?
A: Social mobility
B: Cultural diffusion
C: Ethnocentrism
D: interdependence
The answer that I hope you're looking for is B: Cultural Diffusion.
I hope this helps!