A school is implementing an SAT preparation program. To study the program's effectiveness the school looks at participantsSAT scores before starting the program and after completing the program . The results are shown in the table. How can the values in the Difference row of the table be interpreted?
A. A positive difference means that the students score increased after the program, and a negative difference means that the students score decreased after the program.
B. A positive difference means that the students score decreased after the program, and a negative difference means that the students score increased after the program.
C. A positive difference means that the program was effective, and any negative differences can be ignored.
D. A negative difference means that the program was effective, and any positive difference can be ignored.
