Which one of the following is the best example of quantitative research?
A. Analyzing the essays written by $8^{th}$ grade students across the year to describe the maturation of writing skills
B. Interviewing elementary school students about their perceptions of their teachers at their school
C. Researchers follow the state's Teacher of the Year for an entire semester to document what makes her particularly effective.
D. Looking at school attendance records to identify potential school dropouts
E. Recording the conversations of $2^{nd}$ grade students as they work together to solve a challenging puzzle.