(Last Word)Participation in Company Retirement Savings Programs Has Increased Dramatically

(Last Word) Participation in company retirement savings programs has increased dramatically because:

A) participation was required by the company.
B) enrollment in these programs was set as the default option and workers had to request to be unenrolled.
C) not being enrolled in these programs was set as the default options,and people's aversion to being told what to do prompted many to request enrollment.
D) endowment effects encourage greater saving.