In one study half of a class were instructed to watch exactly 1 hour of television per day, the other half were told to watch 5 hours per day, and then their class grades were compared. In a second study students in a class responded to a questionnaire asking about their television usage and their class grades.

(A) The first study was an experiment without a control group, while the second was an observational study.

(B) The first study was an observational study, while the second was a controlled experiment.

(C) Both studies were controlled experiments.

(D) Both studies were observational studies.

(E) Each study was part controlled experiment and part observational study.