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Answer: self production
Explanation: Plants tends to manufacture for them self unlike animals, they use the energy gotten from the sun to convert carbon dioxide and water in energy rich sugar called glucose.
Also plants use leaves to make food for them self, oxygen is produced as a by-product and carbon dioxide is gotten from the atmosphere.
it depends on the size of the meteor because if it was armagedon then world nasas would come together with nukes from alot of countryies to stop it because it would be like 131 degrease on earth for like a year so it would be the most reasonable way to stop it
