How can a vaccine change how people encounter diseases in their environment?

Which situation is most likely to show a constant rate of change?

What name is given to the money that had to be paid by germany in ww2

Sariah enters a room with several chirping crickets in it. upon first entering the room, sariah can hear the chirping; however, as she begins to talk to her friends, she is no longer aware of the chirping even though it is still there. the fact that sariah no longer perceives the chirping sound demonstrates sensory