prep 的一道逻辑题 关于补充句子的

which of the following most logically
completes the argument?

When people engage in activities that help
others, their brain releases endorphins, the brain’s natural opiates, which
induce in people a feeling of well-being. It has been suggested that regular
release of endorphins increase people’s longevity, and a statistic on adults
who regularly engage in volunteer work helping others shows that they live
longer, on average, than adults who do not volunteer. However,
that statistic would be what we would expect even if volunteering does not
boost longevity, since--------

A. In the communities studied, women were
much more likely to do regular volunteer work than men were, and women tend to
live longer than men do

B. The number of young adults who do
regular volunteer work is on the increase

C. The feelings of well-being induced by
endorphins can, at least for a time, mask the symptoms of various conditions and
diseases, provided the symptoms are mild

D. it is rare for a person to keep up a
regular schedule of volunteer work throughout his or her life

E. some people find that keeping a
commitment to do regular volunteer work becomes a source of stress in their
lives.