The Essential Difference Between an Experiment and an Observational Study

Multiple Choice

The essential difference between an experiment and an observational study is that

A) observational studies always involve large numbers of subjects, but experiments never do.
B) in an experiment, information is gathered only on animals or things, but in an observational study, only information about people is gathered.
C) an observational study imposes treatments on the subjects, but an experiment does not.
D) observational studies cannot have variables.
E) an experiment imposes treatments on the subjects, but an observational study does not.