Change the following from active to passive: The research team will have reverified the samples before sunrise.

The correct option is (b). The active sentence is in the future perfect tense: will have reverified. While converting active to passive, we must keep the tense unchanged and make the object of the active sentence the subject of the passive sentence. Active structure (Future Perfect): Subject + will have + V3 + object. Passive structure (Future Perfect): Object + will have been + V3 + by + subject. Here: Subject: The research team Verb: will have reverified Object: the samples So, passive becomes: The samples will have been reverified by the research team before sunrise. This exactly matches option (b). Why other options are incorrect: Option A changes the tense to present perfect (have been), which is incorrect. Option C changes the tense to simple future (will be), which is incorrect. Option D is grammatically wrong because been reverifying is not the correct passive construction here, and would have changes the meaning. So the correct answer is (b)