to change oxygen into carbon dioxide to break down sugar into usable chemicals to convert energy from sunlight into food energy to allow the passage of carbon dioxide into the plant
I gave my students this multiple choice question: What is the main function of photosynthetic cells within a plant?

Only one answer is correct among these 4 choices:
- to change oxygen into carbon dioxide
- to break down sugar into usable chemicals
- to convert energy from sunlight into food energy
- to allow the passage of carbon dioxide into the plant

Could you tell me which one is correct?

to convert energy from sunlight into food energy