Why is the rainforest referred to as the "lungs of the earth"?

The rainforest is often referred to as the "lungs of the Earth" primarily because it plays a crucial role in the process of photosynthesis, which involves absorbing carbon dioxide and releasing oxygen. During this process, plants in the rainforest utilize sunlight to convert carbon dioxide and water into glucose and oxygen. This significant release of oxygen contributes to maintaining the balance of gases in the atmosphere, making it vital for the survival of many living organisms. Additionally, the large biomass of the rainforest—comprised of diverse plant species—enhances its ability to undertake this vital function, further underscoring its importance in sustaining life on our planet.

While other options highlight important aspects of rainforests, such as their biodiversity and climate regulation, the specific relationship between carbon dioxide uptake and oxygen release underpins why they are metaphorically described as the "lungs."