Early cells likely formed from a group of organic compounds, including proteins, and primitive fatty acids. why do most scientists think that the first true cells formed on earth were anaerobic? a. because they could produce their own oxygen
b. because there was no oxygen on early earth
c. because they make their own food
d. because they use less energy to find nutrients

The reason why nost scientists thought  that the first true cells formed on Earth were anaerobic is being shown in the second option :B. because there was no oxygen on early Earth. Paying attention to this fact scientists discovered that first cells were prokaryotes and greatest part of them created oxygen as a toxic by-product of their own metabolism which make them understand how the planet was provided with oxygen and made a conclusion that first cells were anaerobic.

D.) domain, kingdom, phylum, class, order, family, genus, species