"Moreover, although a large percentage of women than ever before are now entering and remaining in the job market, most continue to gravitate toward the pink-collar fields, despite the lower salaries
The boldfaced is the key. Even though more women are working, most of them choose to do the pink-collar jobs that pay lower salaries. Heck, if they want to get paid more, then they gotta to look for jobs other than the pink-collar ones. (why stick to them?) In other words, "more women must enter occupations other than those traditionally reserved for them." (which is E).
(C) more men must be encouraged to enter fields traditionally occupied by women
is irrelevant because it appears that the salary differences is not due to whether it's men or women doing the job, but largely due to the nature of the job. Pink-collar jobs are traditionally paid less and more men choosing to work in such jobs would not raise the salaries any higher... C assumes that men, by their presence, can increase salaries (maybe just because they're "men" and should be paid more...)