A Tennis Coach Believes Orange Juice Improves Performance

Multiple Choice

A tennis coach believes orange juice improves performance.She gives her players orange juice on randomly chosen days,and rates their performance.What,if anything,is wrong with this study?​

A) People in a control group should drink orange juice on the same days.
B) ​The players should be able to choose when to drink orange juice.
C) ​The study should have a blind observer.
D) ​Nothing is wrong with this study.