A popular conception is that higher pay for teachers is necessary

A popular conception is that higher pay for teachers is necessary to improve the quality of education in public schools. Higher pay will allow the school systems to attract more qualified educators and also to retain those with the best performance. However, recent statistics show that schools with similar average teacher salaries often have widely varying academic results, as measured by students' scores on standardized tests and subsequent grades in college. Clearly, better training for the teachers currently employed would be a more effective method for raising academic quality than would raising teachers' salaries.

The bolded phrases in the argument above play which of the following roles?

A. The first phrase shows that there is no relation between teacher pay and educational quality, and the second provides the conclusion of the argument.
B. The first phrase proves that teachers' salaries do not need to be raised, and the second suggests an alternate method for raising educational quality.
C. The first phrase establishes that other factors affect academic results more than teachers' pay does, and the second concludes that one of those factors should be addressed.
D. The first phrase provides evidence that teachers' pay is not the only determinant of educational quality, and the second advocates action with respect to another such determinant.
E. The first phrase illustrates the need to raise teachers' salaries at some schools, and the second undermines that conclusion by presenting an alternate course of action.