Which of the Following Is True

Which of the following is true?

A) Ling's system of gymnastics were actually quite boring and were not popular in Sweden but did gain some respect in the northeastern United States.
B) Ling developed a life-long interest in the medical effects of exercise because the pain in his arthritic arms were relieved through fencing and associated exercises.
C) Ling developed a system of exercises that positively influenced both the body and mind.
D) Ling did not agree with the approach to exercise used by Jahn and the Turners because they were too complicated.
E) All of the above.