Answer:
b central Africa and the Amazon basin
Explanation:
Selva is a collection of rain forest that is really important for the world's Oxygen production and water reserves. These area have more trees per square of land compared to any other place on the world.
Currently, large portion of it is located in central Africa and Amazon, where industrialization still pretty much non-existent. If we count the production of oxygen made in Amazon alone, it accounted to around 20% of the world's oxygen production.
