"The lungs of the world" - are

Options

A. Plants
B. Planktons
C. Human beings
D. 1 and 2

Answer

**Step-by-Step Solution:**

1. **Understanding the Phrase "Lungs of the World":**
- The term "lungs of the world" refers to entities that play a crucial role in the process of respiration and air purification, similar to how human lungs function.

2. **Identifying the Options:**
- The options provided are:
- A) Plants
- B) Phytoplankton (or just plankton)
- C) Human beings
- D) Both A and B

3. **Analyzing the Role of Plants:**
- Plants, especially trees, are essential for photosynthesis. They take in carbon dioxide (CO2) and release oxygen (O2), which is vital for most living organisms.
- This process purifies the atmosphere, making plants a suitable candidate for the title "lungs of the world."

4. **Examining Phytoplankton:**
- Phytoplankton are microscopic plants found in aquatic environments. They also perform photosynthesis and produce oxygen.
- However, their role is limited to aquatic ecosystems, and they do not contribute to the air quality of terrestrial environments.

5. **Considering Human Beings:**
- Humans do have lungs, but they do not purify the atmosphere in the same way that plants do. Instead, humans consume oxygen and release carbon dioxide.

6. **Conclusion:**
- Since plants (especially trees) are responsible for oxygen production and air purification on a global scale, they are rightly referred to as the "lungs of the world."
- Therefore, the correct answer is **A) Plants**.

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