Which sentence supports the claim that the ancient Greeks thought exercise was worthwhile?

A.
In the early nineteenth century, Jahn created the first gymnastics club.
B.
People would spend as much time exercising as they would working on writing or math.
C.
It helped make the sport popular throughout Germany and later the world.
D.
He thought that the young people of Germany could be encouraged and built up through gymnastics.

D. He thought that the young people of Germany could be encouraged and built up through gymnastics.