The site of water oxidation and source of O2 evolution in photosynthesis lies in:

📌Concept:
-The splitting of a water molecule in the presence of light by green plants is known as the photolysis of water.
-During the photolysis of water, oxidation of water takes place with the release of oxygen.
-It was earlier believed that the source of molecular oxygen released at the end of the photosynthesis process was carbon dioxide.
-Later on due to the works of Robert Hill, it came to be known that the source of oxygen released at the end of the photosynthesis process was water.
-Photolysis of water is part of Photoact II mediated by photosystem II.

✅Explanation:
-Option 1: Inner space or lumen of the thylakoid – CORRECT
-​Photolysis of water is mediated by photosystem II.
-Photosystem II is located on the inner side of the membrane of the thylakoid.
-Light energy splits the water molecule into H+ and OH- ions.
-The H+ ions react with NADP from the stroma of the chloroplast and OH- ions react with hydrogen to produce water and oxygen. Electrons are also released during this process.
-Thus during the photolysis of water (during photosynthesis), sunlight is used to carry out the oxidation of water to release oxygen and protons.
-Option 2: Stroma – INCORRECT
-The second stage of photosynthesis – dark reaction or light-independent reaction – takes place in the stroma of the chloroplast.
-NADPH and ATP formed at the end of the light reaction are utilized in this stage.
-It is a carbon-fixing stage, where CO2 from the atmosphere taken up by the plants is fixed into a sugar molecule.
-Calvin cycle is a carbon fixing stage that place in the stroma of the chloroplast of C3 plants.
-Option 3: Outer surface of thylakoid – INCORRECT
-​Photosystem I is present on the outer surface of the thylakoid.
-Cyclic photophosphorylation takes place in photosystem I.
-During this process, a high-energy electron released from a reaction center (P700) of the photosystem I return to the same reaction center.
-Two ATP molecules are produced at the end of cyclic photophosphorylation.
-Option 4: Cristae – INCORRECT
-Cristae are the inward projections present on the inner membrane of the mitochondria.
-Oxidative phosphorylation takes place in the cristae of the mitochondria.