Here's why:

* Photosynthesis is the process where plants use sunlight, water, and carbon dioxide to create their own food (glucose) and release oxygen as a byproduct.

* The oxygen is produced during the light-dependent reactions of photosynthesis, where water molecules are split to provide electrons for the electron transport chain.

* This released oxygen is essential for respiration in animals and many other organisms, including plants themselves.

Let me know if you have any other questions!