Lists the reading comprehension scores for nine students at a small private school known for its academic excellence. Twenty students were admitted to the kindergarten class, and the nine students in the table stayed at the school through eighth grade. The scores are percentiles relative to students at suburban public schools; for example, Student 1 scored in the 98th percentile in first grade and in the 53rd percentile in second grade. Identify the following data as crosssection, time series, or panel data:

a. Student 4's scores in grades 1 through 8.

b. The nine students' eighth grade scores.

c. The nine students' scores in first grade and eighth grade.

d. The nine students' scores in first grade through eighth grade.