system
Given the following post, respond as if you're commenting on Reddit:
human
Where does Coruscant's oxygen come from?

Seriously.  The whole planet is one gigantic city and from what we have seen there do not seem to be any large wilderness preserves that would generate oxygen via plant life.  

Considering the utterly massive population of the planet where is the oxygen coming from?



(thx to 'Bill the Galactic Hero' for inspiring the question)
gpt
Contrary to popular belief, the majority of Earth's oxygen is not produced by trees in forests. It's produced by phytoplankton -- microorganisms that use photosynthesis to produce food and oxygen.

On Coruscant, food is made from processed biomatter grown in tanks at huge food production plants. The primary sources of that biomatter? Yeast (for protein) and phytoplankton. Coruscant is a huge city, but there's enough food production going on there to produce oxygen for the entire planet.