Producers, like plants and algae, release oxygen (O2) into the atmosphere during photosynthesis.

Here's why:

* Photosynthesis Equation: Photosynthesis is the process where plants use sunlight, water, and carbon dioxide to create their own food (glucose) and release oxygen. The simplified equation is:

6CO2 + 6H2O + sunlight → C6H12O6 + 6O2

* Oxygen as a byproduct: The oxygen released during photosynthesis is a byproduct of the splitting of water molecules (H2O).

This oxygen is essential for many life forms on Earth, including humans and animals, who use it for respiration.