Kinetta is interested in the impact of student mobility on achievement and decides to examine the relationship within the K-4 elementary school at which she teaches. Kinetta defines a mobile student as a student who has been enrolled in three or more schools in the previous two years. If a student's records indicate he or she meets this criterion, the student is considered mobile. Kinetta receives permission to access the records of all fourth grade students in her school. Using these records, Kinetta determines whether each fourth grade student was or was not mobile over the previous two-year period. She also obtains each fourth grade student's scale score on the recently administered MAAP standardized test and plans to compare those scores by mobility status. Identify and name the independent variable(s) [IVs]: a. Achievement on the MAAP test b. Student GPA c. The K-4 school setting d. The status of student mobility