Determine whether the study depicts an observational study or an experiment. A study is conducted to determine if there is a relationship between stomach cancer and alcohol consumption. alcohol consumption. Everyone treated at a hospital for stomach cancer was asked Everyone treated at a hospital for stomach cancer was asked about their alcohol consumption.

a. The study is an experiment because the researchers control one variable to determine the effect on the response variable.
b. The study is an observational study because the researchers control one variable to determine the effect on the response variable.
c. The study is an observational study because the study examines individuals in a sample, but does not try to influence the response variable.
d. The study is an experiment because the study examines individuals in a sample, but does not try to influence the variable of interest.