Phosphorylation of ADP during glycolysis occurs via:

Explanation

During glycolysis, ATP is produced through substrate-level phosphorylation. This process involves the direct transfer of a phosphate group from a high-energy substrate molecule to ADP, forming ATP. This mechanism is distinct from oxidative phosphorylation, which occurs in mitochondria during the electron transport chain, and chemiosmosis, which is part of oxidative phosphorylation. Photophosphorylation is unrelated, as it occurs during photosynthesis in chloroplasts.