The headmaster's reasoning depends upon which of the following assumptions? A. It would be possible to reconfigure the school's schedule to accommodate having math classes in the afternoon. B. Several schools similar to Leawood Day School hold math classes in the afternoon. C. The quality of the teaching has little bearing on test scores. D. This year the math department started using new, unfamiliar curricular materials. E. Students are more likely to be fully awake during the final period of the day than they are during the first period of the day.