b) 3.5 billion years
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D
Oxygen was not present in the early atmosphere b ecause oxygen is a waste product produced by photosynthesizing organisms such as plants and cyanobacteria, which did not exist then.
Or ask the teacher, she/he probably would be pleased to answer. But, reading the book would be a good thing and good practice for the next test.
As you go through adult life, you won't always have a "help desk" available and it is good to learn now how to find things the hard way and determine the best answers on your own.
Hey dear u know only one reason for done that thing that temprature decreases so high temp adopted living being get died hehehhe
pramod
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