The answer to this is cell II. This means that the oxygen will be staying within the special storage granules. Take note that to plants, oxygen is considered to be a waste product. This explains why people need to plant a lot of trees. It will provide people free oxygen while they are living.
A world without oxygen will make it harder for people to breathe. Humans, on the other hand, consider carbon dioxide as a waste product. This is something that plants need in order to photosynthesize. There are just moments when carbon fixation in photosynthesis as well as other problems may occur that can prevent the plant from releasing oxygen.