The oxygen evolved during photosynthesis comes from water molecules. Which one of the following pairs of elements is involved in this reaction?

The breakdown of water molecules into hydrogen and oxygen in the presence of light, during the light reaction of photosynthesis is called photolysis of water. The micronutrients manganese and chlorine are involved in the photolysis of water. The other options given in the question have following functions:• Magnesium- It is a component of chlorophyll and an activator of enzymes involved in respiration and photosynthesis.• Potassium- It is required as a cofactor for many enzymes and maintains membrane permeability, turgidity of cells, and anion-cation balance in cells.• Molybdenum- It is a component of the enzyme nitrate reductase and is involved in nitrogen metabolism. So, the correct answer is 'Manganese and Chlorine'.