According to the text, what is the central obstacle in the search for extraterrestrial organisms?

Answer

The tenacity and adaptability of microscopic life hitchhiking from Earth.

The adaptability of terrestrial microscopic residents, like bacteria and fungi, which survive in space environments, presents the central obstacle by confusing findings and casting doubt on potential extraterrestrial origins.

According to the text, what is the central obstacle in the search for extraterrestrial organisms?
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