How is this comic strip evidence of cultural diffusion?

This comic strip is evidence of cultural diffusion because it shows how the idea of celebrating Halloween has spread from its origins in ancient Celtic culture to become a widely celebrated holiday in contemporary America. The comic strip depicts a scene where Charlie Brown and his friends are preparing for Halloween by dressing up in costumes and trick-or-treating, which are customs that originated in Celtic traditions. This illustrates how cultural practices and traditions can travel across regions and become adopted by different societies, showcasing the process of cultural diffusion.