Which statement best explains the relationship between the electron transport chain (ETC) and redox reactions in microbial metabolism?

• A. The ETC functions by creating ATP directly from redox reactions without proton gradients.
• B. The ETC involves a series of redox reactions that pump protons across a membrane, generating a proton motive force used to synthesize ATP.
• C. The ETC is only used during fermentation and not during respiration.
• D. The ETC bypasses redox reactions by using ATP hydrolysis to generate a proton gradient.

Answer: (B)