The increase in atmospheric carbon dioxide 3.5 billion years ago would have likely been contributed to by a) early cells undergoing anaerobic lactic acid fermentation. b)early cells using hydrogen sulfide in the formation of biomolecules. c)early cells beginning the process of photosynthesis and producing sugars. d)increasing colonies of cyanobacteria undergoing photosynthesis.

The answer is B. This is stipulated in the theory of abiogenesis. The atmosphere in early earth was composed of compounds such as methane, hydrogen sulfide, and ammonia. This reducing environment was right for the formation of biomolecules . This early life is similar to that found in hydrothermal vents deep in the oceans, today.

c: warm water flows from the western tropical pacific toward south america. that should be the right answer! hope it .