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 increases 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, because ________________________
Which of the following most logically completes the argument?
So volunteering has been connected to longevity, and there seems to be a causal connection - volunteering causes the release of endorphins, and the regular release of endorphins increases people's longevity.
The sentence with the blank seems to be discussing a different connection between volunteering and longevity, maybe one that is not causal. So maybe an answer choice that includes a different connection will be the best one to fill that blank.
I am not even going to speculate regarding what the alternate connection might be. I am just going to look for one in the answer choices, and if there isn't one in the answer choices, then I will look for another way to fill that blank.
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.
Bingo, an alternate connection. Is this the best answer? Almost definitely, because it provides an alternate, non causal connection between volunteering and longevity. I am still going to check the rest of the choices, but I am confident this is the right answer.
B) The number of young adults who do regular volunteer work is on the increase.
This does not explain why people who volunteer live longer. It may be a trap answer, because younger people may have longer to live than older people, but having many years more to live is not the same as having greater longevity.
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.
Masked symptoms are not the same as longevity, and also this choice still seems to causally connect volunteering to endorphins and thus longevity. So this does not provide an alternate explanation, and it is not the answer.
D) It is rare for a person to keep up a regular schedule of volunteer work throughout his or her life.
If I make up some story about people who do rare things living longer, then this answer choice could connect volunteering and longevity. Making up stories that cannot clearly be inferred from the prompt or answer choices is a common way people get CR questions wrong though. Without such a story this does not connect longevity and volunteering. So I am not going to choose it.
E) Some people find that keeping a commitment to do regular volunteer work becomes a source of stress in their lives.
If anything, this would actually weaken the connection between volunteering and longevity.
So A is the best choice.
I can't seem to understand how A seems to disconnect Volunteering from Longetivity 
