Q19: PP74. Why notD

A recently published report indicates that the salaries of teachers continue to lag far behind other college-educated professionals, because they make an average of nearly $8,000 a year less at the start of their careers and almost $24,000 less a year by the time they reach the age of 50.

A.      other college-educated professionals, because they make an average of nearly $8,000 a year less at the start of their careers and almost $24,000 less

B.      other college-educated professionals, by an average of nearly $8,000 a year at the start of their careers, to almost $24,000

C.      what other college-educated professionals are paid—making an average of nearly $8,000 a year less at the start of their careers and almost $24,000 less

D.      those of other college-educated professionals—by an average of nearly $8,000 a year at the start of their careers to almost $24,000 less

E.       those of other college-educated professionals—by an average of nearly $8,000 a year at the start of their careers, and by almost $24,000

这道题我也选错了，我也选了D，我感觉应该是语意的问题吧

A选项用的就是and 而D选项用的是to

and是一种并列的描述，而to则有了一个方向性

个人理解……