Biologists are not sure about how many prodaryotic species on earth might be present. The problem is that

Options

A. Conventional taxonomic methods are not suitable for identifying microbial species
B. Many prokarotic species are simply not culturable under laboratory conditions
C. Microbes are too small so not easily visible under the microscopes
D. Both A and B

Answer

D

Explanation

Biologists are not sure about how many prokaryotic species there might be. The problem is that conventional taxonomic methods are not suitable for identifying microbial species and many prokaryotic species are simply not culturable under laboratory conditions.