GMAT Sentence Correction (SC) | Re: Bioconservatives, a group who believe

Hi expert,
I have doubts with the construction of the correct option B.
1) Bioconservatives,a group who...
How can who refer to group correctly?
2) Bioconservatives...predict
If we treat "Bioconservatives" as a group,how can we use the plural verb "predict"

Please help clarify my doubt
Thanks

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