Recent metagenomic investigations reveal that human microbial flora is extremely diverse and is best described a

Beneficial and harmful microbial flora

Explanation:

Human microbial flora is extremely diverse and is best described as beneficial and harmful microbial flora because some microbial flora are good for living organisms and environment while others are harmful means causes damage to organisms and the environment. Microbial flora refers to those microorganisms which have similar characteristics to plants. Some examples of microbial flora are Staphylococcus epidermidis, Corynebacterium spp, Streptococci and Neisseria spp etc.

correct answer is option a.

tropopause, stratopause and mesopause have all in common aspect that is point of maximum temperature in its layer of the atmosphere. all layers of atmosphere observe abrupt change in temperature. tropopause is the boundary between troposphere and stratosphere. stratopause is the boundary between stratosphere and mesosphere. mesopause is the boundary between mesosphere and thermosphere. these all boundaries are ranges between altitude of 0 to 80 km.

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