The source of oxygen evolved during photosynthesis is

Which two unicellular algae were used by Ruben and Kamen to confirm that the source of oxygen evolved during photosynthesis was water.

The source of oxygen generated during photosynthesis is :

The source of oxygen liberated during photosynthesis is:

What is the source of oxygen released during photosynthesis ?

Oxygen evolved during photosynthesis comes from

………… is evolved during photosynthesis.

What is the source of oxygen liberated in photosynthesis ?