Select all the correct answers. An athletic coach conducted an experiment to test whether a four-week stretching and flexibility program reduces the number of muscular injuries that occur during athletic events. The coach randomly selected 30 athletes from several sports and randomly assigned 15 athletes to the four-week program. The remaining 15 athletes did not participate in any type of flexibility program during the four weeks.

Which statements about this study are true?

a. This study uses blocking.
b. This study uses blinding.
c. This study uses a repeated measures design.
d. This study uses random sampling.
e. This study uses a control group.