A teacher is trying a new strategy of daily communication to encourage students to study more. She tests her new strategy on a random sample of her students. She then surveys all her students after two weeks, right before their first exam, to see how much they had studied. She predicts that the students who received the daily communications studied more. What is the response variable for the experiment? a. Whether students received the daily communication or not. b. Whether students read all the daily communications. c. Students' score on their first exam. d. How much the students had studied. a Ob