Answer:The answer is tiny organisms known as cyanobacteria, or blue-green algae.
Explanation:
These microbes conduct photosynthesis: using sunshine, water and carbon dioxide to produce carbohydrates and oxygen increase. Additionally, some sources you could use that I used to answer this question was 
https://www.scientificamerican.com/article/origin-of-oxygen-in-atmosphere/
 
        
             
        
        
        
Answer:
Australia
Explanation:
it is 2.968 million square miles, therefore making it the largest country in Oceania.
 
        
             
        
        
        
Answer:
casandra was scared around others
Explanation:
in the passage i notesed that she went to her locker and started crying