In oxidative phosphorylation, what is the primary purpose of the electron transport chain (ETC) in the inner mitochondrial membrane?

• A. To directly catalyze the phosphorylation of ADP to ATP by substrate-level phosphorylation
• B. To oxidize glucose to pyruvate in the mitochondrial matrix
• C. To use energy from electron transfer to pump protons (H${+}^{}$) across the inner mitochondrial membrane, generating a proton-motive force that drives ATP synthesis
• D. To transport ATP out of the mitochondrial matrix by moving it through Complex IV

Answer: (C)