Researchers Use Randomized Clinical Trials to Determine the Effectiveness and Safety

Researchers use randomized clinical trials to determine the effectiveness and safety of therapeutic treatments.Which of these is the key element in this kind of research?

A) include the treatment in a group of randomly chosen treatments and apply all of them to participants
B) compare the treatment one group gets with a control group condition to see if there is any difference
C) perform the treatment trials in a clinical setting
D) Researchers experience the treatment before actual clients or patients to ensure safety.