The part labelled I in the diagram refers to **sunlight**.
Here's a simple explanation:
The given chemical equation is a representation of **photosynthesis**, a process by which green plants, algae, and some bacteria convert light energy, typically from the sun, into chemical energy stored in glucose (C6H12O6) and release oxygen (O2) as a by-product.
In the context of the equation:
- **6CO2 (Carbon Dioxide) + 6H2O (Water) → C6H12O6 (Glucose) + 6O2 (Oxygen)**
The arrow indicates the transformation that occurs during the process. The **chlorophyll** (labelled in the diagram) indicates the presence of chlorophyll pigments in the chloroplasts of plant cells which are essential for **absorbing sunlight**.
Since **sunlight** is the source of energy that powers this transformation, it is the correct component for the part labelled I in the diagram.