The component of air used by green plants to make their food, is _________

Explanation

To solve the question about the component of air that green plants use to make their food, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Components of Air**:
- Air is made up of various gases, including nitrogen, oxygen, carbon dioxide, argon, and water vapor.

2. **Understand the Process of Photosynthesis**:
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