It is a codon. A codon codes for Amino acids and an Anti-codon Codes for the breakdown of Amino Acids.
Oxygen.
Oxygen was fatal when organisms started using photosynthesis, this event was known as the Great Oxidation Event.
31c-11c=20c So, therefore, the range is 20c.
Hope this helps! :D
D. hormones would be the correct answer, which are chemical substances produced by gakbdd