ExplanationThe sentence tells you that there was no plant life in the area before, based on the time trigger word previously. Furthermore, if humans will be able to live in the area some day, then you know that plant life being described, must be alive and flourishing. This eliminates static, waning, and flagging. Fervent is used to describe human feelings or something that is very hot, so it does not work in this context. Incipient and nascent both mean that the plant life has recently come into being and are the correct answers.
Hence options A and B are correct!
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