Determine whether the study depicts an observational study or an experiment.
Fifty patients with lung cancer are divided into two groups. One group receives an experimental drug to fight cancer comma the other a placebo. After two years comma the spread of the cancer is measured.
Question content area bottom
Part 1
Does the description correspond to an observational study or an​ experiment?
A.
The study is an observational study because the study examines individuals in a sample comma but does not try to influence the response variable.
B.
The study is an experiment because the study examines individuals in a​ sample, but does not try to influence the variable of interest.
C.
The study is an experiment because the researchers control one variable to determine the effect on the response variable.
D.
The study is an observational study because the researchers control one variable to determine the effect on the response variable.