Here's why:

* Bases are not inherently oxygen-producing: Bases are chemical compounds that typically release hydroxide ions (OH-) when dissolved in water. They don't directly contain or produce oxygen.

* Oxygen production requires other processes: Oxygen is primarily produced through photosynthesis in plants and algae. It's also a byproduct of some chemical reactions, like the electrolysis of water.

To clarify, here are some examples of how oxygen is produced:

* Photosynthesis: Plants use sunlight, water, and carbon dioxide to produce glucose (sugar) and oxygen.

* Electrolysis of water: Passing an electric current through water breaks it down into hydrogen and oxygen gas.

In summary, while bases are important in many chemical reactions, they do not produce oxygen in water.