The correct option is Amazon rainforest.
Explanation
Biomes are large ecological areas on the Earth's surface, with fauna and flora adapting to their environment. Tropical rainforests are biologically diverse ecosystems characterized by high rainfall and dense vegetation, playing a pivotal role in the global carbon cycle and atmospheric regulation.
- Amazon rainforest is Correct: The Amazon rainforest is widely known as the "lungs of the planet." It is the largest tropical rainforest in the world and is estimated to produce approximately 20% of the Earth's oxygen through the process of photosynthesis. Furthermore, it acts as a massive carbon sink, absorbing significant amounts of carbon dioxide from the atmosphere.
- Taiga is Incorrect: The Taiga, also known as the boreal forest, is the world's largest terrestrial biome consisting mainly of coniferous forests. While it stores large amounts of carbon in its soil and trees, the specific epithet "lungs of the planet" is reserved for the Amazon due to its higher rate of oxygen production and biodiversity.
- Tundra is Incorrect: The Tundra is a biome characterized by frost-molded landscapes, extremely low temperatures, little precipitation, poor nutrients, and short growing seasons. It lacks the dense tree cover required for massive oxygen production comparable to rainforests.
- Savanna is Incorrect: The Savanna is a rolling grassland scattered with shrubs and isolated trees. While it is an important ecosystem, its contribution to global oxygen levels is significantly lower than that of the dense tropical rainforests.
Key Takeaway: The Amazon rainforest is critical to global climate stability and is termed the "lungs of the planet" because of its vast contribution to global oxygen production and carbon sequestration.