Answer:
It is an observational study
Explanation:
It should be understood that an observational study is an empirical but non-experimental investigation of the effects caused by a treatment.
In this aspect, the researchers observe the effect of a risk factor, diagnostic test, treatment or other intervention without trying to change who is or isn't exposed to it. The simply collect data based on what is seen and heard and infer based on the data collected.
In this case, the medical researcher was trying to know the effect of the new medicine by observing the reactions of the participants to the drug. He also made use of placebo to serve as a control.
Note that, placebo is made to look exactly like a real drug but is made of an inactive substance, such as a starch or sugar, and use in research studies.
They are used in studies in order to find out whether or not the pharmacological effect of a drug actually includes pain relief or whether the effects produced by the drug might be related to psychological processes that are generically called the placebo effect.