The gas given out by green plants during process of photosynthesis is

Options

A. carbon dioxide
B. nitrogen
C. oxygen
D. None of these

Explanation

To answer the question about the gas given out by green plants during the process of photosynthesis, we can follow these steps:

### Step-by-Step Solution:

1. **Understand Photosynthesis**: Photosynthesis is the process by which green plants, algae, and some bacteria convert light energy into chemical energy in the form of glucose. This process primarily occurs in the chloroplasts of plant cells.

2. **Identify the Inputs**: The main inputs for photosynthesis are carbon dioxide (CO2) and water (H2O). Plants take in carbon dioxide from the atmosphere through small openings in their leaves called stomata.

3. **Identify the Outputs**: The outputs of photosynthesis are glucose (C6H12O6) and oxygen (O2). The glucose produced is used by the plant for energy and growth, while oxygen is released as a byproduct.

4. **Chemical Equation**: The overall chemical equation for photosynthesis is:
\[ 6 \text{CO}_2 + 6 \text{H}_2\text{O} \xrightarrow{\text{sunlight}} \text{C}_6\text{H}_{12}\text{O}_6 + 6 \text{O}_2 \]
This equation shows that six molecules of carbon dioxide and six molecules of water, in the presence of sunlight, produce one molecule of glucose and six molecules of oxygen.

5. **Conclusion**: From the chemical equation and the process of photosynthesis, we can conclude that the gas released by green plants during photosynthesis is oxygen (O2).

### Final Answer:
The gas given out by green plants during the process of photosynthesis is **C. oxygen**.

---