Maximum `O_2` evolution occurs from

Options

A. Forests
B. Marine phytoplankton
C. Crops
D. Land mass

Answer

To determine where the maximum O2 evolution occurs, we need to analyze the options provided and understand the role of different organisms in photosynthesis.

### Step-by-Step Solution:

1. **Understand the Options**: The options given are:
- A) Forest
- B) Marine Phytoplankton
- C) Crops
- D) Land Mass

2. **Evaluate Each Option**:
- **Forests**: While forests are significant contributors to oxygen production through photosynthesis, they are not the sole or maximum contributors.
- **Marine Phytoplankton**: These are microscopic plants found in oceans that perform photosynthesis. They are known to produce a substantial amount of oxygen.
- **Crops**: Agricultural crops also contribute to oxygen production but are limited to specific land areas.
- **Land Mass**: This is a broad category that includes various ecosystems, but it does not specifically indicate a high concentration of photosynthetic organisms.

3. **Focus on Marine Phytoplankton**: Research and scientific consensus indicate that marine phytoplankton are responsible for producing a significant portion of the Earth's oxygen. It is estimated that they contribute between 50% to 85% of the oxygen in the atmosphere.

4. **Conclusion**: Based on the analysis, the option that represents the maximum O2 evolution is **B) Marine Phytoplankton**.

### Final Answer:
Maximum O2 evolution occurs from **Marine Phytoplankton** (Option B).

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