In simple words, A randomised controlled trial (RCT) is a form of academic study or intervention research that tries to eliminate some forms of prejudice when assessing the efficacy of novel therapies by arbitrarily assigning people to two or more subgroups administering them differentially, and then evaluating their responses.
Thus, from the above we can conclude that the correct answer is randomized control trial.
It took 1 year to travel from one end of the Islamic empire to the other. Baghdad was the fabled city of wealth that existed at the heart of the Islamic Empire :)