Molecular oxygen is released during:

Explanation

The light-dependent reactions of photosynthesis, also known as the light reactions, occur in the thylakoid membranes of chloroplasts and are responsible for the release of molecular oxygen. During these reactions, light energy is absorbed by chlorophyll, which drives the photolysis of water. This process splits water molecules into hydrogen ions, electrons, and oxygen atoms. The oxygen atoms then combine to form molecular oxygen (O2), which is released as a byproduct. This is the source of atmospheric oxygen replenishment.In contrast, the Calvin cycle (Option A) focuses on the fixation of carbon dioxide and does not produce oxygen. The Krebs cycle (Option C) and glycolysis (Option D) are part of cellular respiration, not photosynthesis, and do not release molecular oxygen.