Question

the oxygen produced during photosynthesis comes directly from the
mitochondrial membranes.
splitting of carbon dioxide molecules.
absorption of light.
splitting of water molecules.

Explanation:

In photosynthesis, the light - dependent reactions involve the splitting of water molecules ($\ce{H_2O}$) into hydrogen ions, electrons, and oxygen gas ($\ce{O_2}$). Mitochondrial membranes are related to cellular respiration, not the production of oxygen in photosynthesis. Splitting carbon dioxide is part of the Calvin cycle (light - independent reactions) and does not produce oxygen. Absorption of light is used to provide energy for the reactions but does not directly produce oxygen. So the oxygen produced during photosynthesis comes directly from the splitting of water molecules.

Answer:

Splitting of water molecules.