Synthesis of ADP + Pi ⟶ ATP in grana photosynthesis

Answer: Option B

The synthesis of ADP + Pi ⟶ ATP in grana photosynthesis is Photophosphorylation.
In the process of photosynthesis, the phosphorylation of ADP to form ATP using the energy of sunlight is called photophosphorylation.
In photophosphorylation, light energy is used to pump protons across a biological membrane, mediated by the flow of electrons through an electron transport chain.
This stores energy in a proton gradient. As the protons flow back through an enzyme called ATP synthase, ATP is generated from ADP and inorganic phosphate.