Which of the Following Statements Is TRUE

Which of the following statements is TRUE?

A) The NADH dehydrogenase complex does not pump protons across the membrane.
B) The pH in the mitochondrial matrix is higher than the pH in the intermembrane space.
C) The proton concentration gradient and the membrane potential across the inner mitochondrial membrane tend to work against each other in driving protons from the intermembrane space into the matrix.
D) The difference in proton concentration across the inner mitochondrial membrane has a much larger effect than the membrane potential on the total proton-motive force.