A school introduced an after-school tutoring program to improve students' math performance. However, math test scores did not improve after the program was implemented. Which of the following, if true, best explains this outcome? (A) The tutoring program focused on general study skills rather than math-specific content. (B) Many students who participated in the program reported feeling more confident in math. (C) The program was optional, and only a small percentage of students attended regularly. (D) The school also introduced a new math curriculum during the same period. (E) Students who participated in the program were already performing well in math