Which statement BEST describes the forgetting functions that Ebbinghaus discovered?

a) Material is forgotten at a relatively constant rate once it has been learned
b) Nothing is ever really forgotten
c) Material is forgotten at a relatively slow rate at first, and then the rate of forgetting speeds up
d) material is forgotten relatively rapidly at first, and then the rate of forgetting slows down

Ans: d) material is forgotten relatively rapidly at first, and then the rate of forgetting slows down