Answer:
Cyanobacteria are responsible for first adding oxygen to the Earth's atmosphere.
CHON is a mnemonic acronym for the four most common elements in living organisms: carbon, hydrogen<span>, </span>oxygen<span>, and nitrogen.</span>
Recombinant DNA is formed when the DNA from one organism is incorporated into the DNA of another organism of the same or different species...
I think the answer would become C or B.
Hopefully this helps!