The scenario that best describes an effect of the diffusion of U.S. culture is:
A person in Paris, France, takes their date to a fast-food restaurant for dinner.
This example illustrates the spread of American fast-food culture to other countries, which is a clear effect of cultural diffusion from the United States. The other scenarios, while they may involve aspects of cultural exchange, do not specifically illustrate the diffusion of U.S. culture in the same direct way.