Chang described two substances which participate in photosynthesis.

Substance A: Helps plants absorb sunlight.
Substance B: Gas formed with glucose.

Which statement is correct?

- Substance A is chlorophyll and Substance B is oxygen.
- Substance A is oxygen and Substance B is carbon dioxide.
- Substance A is glucose and Substance B is carbon dioxide.
- Substance A is carbon dioxide and Substance B is oxygen.