A therapist believes that the music a child listens to may have an impact on the amount of words on a list they can memorize. In order to test this, she selects a random sample of children for an experiment. She has the children look over a list of one hundred words for five minutes while listening to classic rock music. After the five minutes, she tests the children to see how many words they could remember in the order of the list. She then does the same experiment, this time with a different list of words, while listening to classical music. If we let d=classical−classic rock, identify the null and alternative hypotheses for an appropriate hypothesis test.