The conclusion is non causal.
Conclusion - The number of social work volunteers will NOT decrease even if volunteering does not boost longevity.
You need to find a non causal connection to strengthen the last line.
A - is the alternate explanation. Women by habit are nicer and do more volunteering than men. There is no causal connection between longevity and volunteering. So you got the Z factor (the third factor) which directly weakens the causal connection (volunteering X leading to Y longevity)
B - Irrelevant
C - C is again causal connection (X leads to Y). You may want to go at 180 degree.
D - Irrelevant.
E - Contradicts the premise. Its a strict NO NO.
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