An _______ entails modifying a treatment group, while an _______ entails the study of a treatment group according to their present behavior.
A. experiment; experiment
B. observational study; observational study
C. observational study; experiment
D. experiment; observational study
Answer:D
An _______ entails modifying a treatment group, while an _______ entails the study of a treatment group according to their present behavior.
A. experiment; experiment B. observational study; observational study C. observational study; experiment D. experiment; observational study