During the flu season each year, the U.S. Centers for Disease Control and Prevention (CDC) monitors the locations in which flu cases have been identified and tracks the number of cases reported, by state. The spread of the flu demonstrates

(1 point)
Responses

stimulus diffusion.
stimulus diffusion.

contagious diffusion.
contagious diffusion.

hierarchical diffusion.
hierarchical diffusion.

distributed diffusion.
distributed diffusion.

relocation diffusion.