Protons are pumped across the mitochondrial inner membrane as electrons are transferred through the mitochondrial electron transport chain. which of the following statements about proton pumping are correct? choose one or more: a. protons are pumped into the matrix of the mitochondria. b.the nadh dehydrogenase, cytochrome b-c1, and cytochrome oxidase complexes all pump protons across the membrane. c.the ph inside the mitochondrial matrix is higher than in the intermembrane space. d.the mitochondria use the proton gradient to synthesize atp.