Which Phenomenon/phenomena Did Ebbinghaus Observe? (Select All That Apply

Which phenomenon/phenomena did Ebbinghaus observe? (Select all that apply.)

A) Performance on memory experiments was not affected by practice.
B) Spaced repetition was more effective than massed repetition.
C) Recall rapidly declined over the first hour following training.
D) Recall continued to decline after an hour but at a faster rate.
E) Recall declined slowly at first but accelerated after an hour.