PLZZZZZ HURRY!!!!!Scientists estimate that the Earth formed some 4.6 billion years ago with the first forms of life appearing ar
ound 3.5 billion years ago. These first forms of life were simple prokaryotes. Later, the first photosynthetic organisms resulted in more _____________ in the atmosphere. This allowed for more higher level organisms to appear on Earth. A) carbon
B) nitrogen
C) oxygen
D) sulfur
