Forest is also called the Lung of Earth because they absorb a large amount of carbon dioxide from the atmosphere and release oxygen into the atmosphere.
The Amazon rainforest functions as a giant air machine that absorbs a large amount of carbon dioxide, and produces oxygen. More than 20 per cent of the world oxygen is produced in the Amazon Rainforest.
Hence Forest is also called a Lung of Earth.
So, the correct answer is 'Lung of Earth'.
The branchy part of a tree above the stem is known as