In aquaria, green plants are grown for
(a) `Co_(2)` production
(b) Starch production
(c) `O_(2)` production
(d) Increase beauty

Options

A. `Co_(2)` production
B. Starch production
C. `O_(2)` production
D. increase beauty

Answer

To answer the question regarding why green plants are grown in aquaria, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Aquaria**: Aquaria are artificial ecosystems that contain both aquatic plants and animals. These ecosystems are maintained by humans for various purposes.

2. **Role of Aquatic Plants**: In these ecosystems, aquatic plants play a crucial role. They are autotrophic organisms, meaning they can produce their own food through photosynthesis.

3. **Photosynthesis Process**: During photosynthesis, aquatic plants utilize sunlight, carbon dioxide (CO₂), and water to produce glucose and oxygen (O₂). The oxygen produced is a byproduct of this process.

4. **Oxygen Requirement of Aquatic Animals**: The animals in the aquarium are heterotrophic, meaning they cannot produce their own food and rely on consuming other organisms. They require oxygen for respiration, which is essential for their survival.

5. **Conclusion**: Therefore, the primary reason for growing green plants in aquaria is to produce oxygen (O₂) through photosynthesis, which is then used by the aquatic animals for respiration.

### Final Answer:
The correct option is (c) O₂ production.

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