Determine whether the study depicts an observational study or an experiment.

Students are randomly divided into two groups. One group is taught German in a primarily oral class the other is taught German in a primarily written class. After 1 semester, each group is given a German test to compare fluency.

Choose the correct description of the study

a. The study is an experiment because the study examines individuals in a sample, but does not try to influence the variable of interest.
b. The study is an observational study 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.