Reservoir is the answer to your question.
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D the correct answer is d
Because Precambrian rocks are in short supply, hence fossil evidence is harder to find.they only discovers sections of some Precambrian rocks there were no bones or shells to be permineralized.
I'm not 100% sure which biology class you are in are you doing the moth activity? If so then I would believe that the light moth would be easier to see on a dark tree trunk