GMAT Critical Reasoning (CR) | Re: One good clue as to which geographical regions

One good clue as to which geographical regions an ancient relic was moved through in the past involves the analysis of pollen that clings to the surface of the relic. A relic is linked to a geographical area by the identification of pollen from plants that are known to have been unique to that area.

Which one of the following, if true, casts the most doubt on the reliability of the method described above?

(A) Pollens are often transported from one region to another by wind or human movement.
(B)