ATP synthesis proposed by Peter Mitchell is
A. Phosphorylation
B. Phosphorylation
C. Oxidative phosphorylation
D. Cemiosmostic synthesis

Hint: The hydrogen ion gradient produced by the electron transfer chain is utilized by ATP synthase to produce ATP in oxidative phosphorylation. The changing of this molecular system controls the potential energy kept in the hydrogen ion gradient to add up a phosphate to ADP, forming ATP.

Complete Answer:
ATP synthesis associated with the transport of electrons from the inner membrane region via the innermost membrane, back to the matrix. The transport of electrons from the matrix to the inner membrane region causes a considerable pH difference between the two parts of the membrane. Mitchell recognized that this represents a large energy difference, because the chemiosmotic potential is actually composed of two components.

 Now, let us find the solution from the option.
- Phosphorylation is a biochemical process that involves the addition of phosphate to an organic compound.
- During the process of photosynthesis, the phosphorylation of ADP molecules to produce ATP utilizing the power of sunlight is called photophosphorylation.
- Peter Mitchell proposed a theory to explain the production of ATP which is 'Mitchell's chemiosmotic coupling hypothesis'. According to this theory:
- Inner membrane of mitochondria acts as a transducer of energy and converts energy to chemical energy of ATP along the electrochemical gradient.
- Inner mitochondrial membrane is impermeable to NADH, ATP, $H^+$, $OH^-$.
- ATP synthesis and electron transport are coupled with proton gradient.

Thus, the correct option is D. i.e. Cemiosmostic synthesis.

Note: The chemiosmotic hypothesis was reported by Peter Mitchell. This phenomenon stated that a proton-motive force was the reason for initiating the production of ATP.
- In this synthesis, protons would be transferred via the inner mitochondrial membrane as electrons pass via the electron transport chain. Because of that proton gradient pH is lower in the inter membrane region and raised up pH in the matrix of the mitochondria.
- An intact inner mitochondrial membrane, penetrable to protons, is a need of this model.