Answer:
The third friend is correct.
Explanation:
Plants use photosythesis whenever there is a powerful enough light source to do so. They use the ATP from photosythesis to drive cellular respiration, which is how they get large amount of ATP, photosythesis just get the correct materials needed to do so. And while phototsytheis does slow down significantly at night, some plants(like in the desert), do use it at night simply because those conditions are easier for the plant to use photosytheis. Keep in mind that photosythesis uses Carbon dioxide and releases oxygen, and in the calvin cycle, carbon is still used, and oxygen is used to a very minor extent.
