1. A pharmaceutical company develops a new drug to improve balance among the elderly. The new drug is recommended for individuals over 60 years of age to prevent unintentional falls. Investigators enroll 200 study participants in a randomized-controlled trial to evaluate the effectiveness of the drug at preventing falls. Half of the study participants are randomized to receive the new drug while the other half are randomized to receive a control treatment. At the end of a one-year follow-up period, the investigators determine whether the number of falls for each study participant was low (0-2 falls), moderate (3-5 falls), or high (6 or more falls) as a measurement of the primary outcome (unintentional falls). Which of the following best describes the primary outcome variable of this study?