Cyanobacteria which is a type of algae. It conducts photosynthesis and without it there may not have been life today because they didn't need oxygen to survive and in order to have oxygen there had to have been some form of life...
C.18
in middle school we are told the levels are 2,8,8 but once you reach high school, you find out the third level actaully can hokd up to 18.
Answer:
To prevent a pathogen infection
I would say the growth, the repair, and the reproduction.
