How is the energy used to make ATP via the electron-transport chain generated?

A)The energy from electrons bound to reduced coenzymes is used to create a steep electrochemical gradient.
B)Electrons bound to NADH are used to generate an H⁺ ion gradient across the inner mitochondrial membrane.
C)Electrons bound to FADH₂ are used to generate a proton gradient across the inner mitochondrial membrane.
D)Electrons bound to NADH are used to generate a proton gradient across the inner mitochondrial membrane.
E)All of these are correct.