Answer:
B. The spread of baseball to Japan.
Step-by-step explanation:
While the invention of the airplane increased the cross-cultural contacts, it is not an example of diffusion of culture. It simply made diffusion easier. The isolation of cultures prevent diffusion of culture. A large population also increases the chances of cross-cultural diffusion, but it is not an example of cultural diffusion. The spread of baseball to Japan illustrates the adoption of a cultural idea by a different culture: A diffusion of culture.