The chemiosmotic theory of oxidative phosphorylation suggests that adenosine triphosphate $(ATP)$ is produced because:

• A
  $A$ proton gradient is formed across the inner membrane.
• B
  The permeability of the outer mitochondrial membrane to adenosine diphosphate $(ADP)$ changes.
• C
  The permeability of the inner mitochondrial membrane to adenosine diphosphate $(ADP)$ changes.
• D
  $ADP$ is pumped from the matrix into the intermembrane space.