Final answer:
Electrons in the electron transport chain transfer energy that is used to pump hydrogen ions across the mitochondrial membrane, creating a gradient that drives the synthesis of ATP through chemiosmosis. The correct option is B.
Step-by-step explanation:
The role of electrons in the electron transport chain is to facilitate the production of ATP through a process known as oxidative phosphorylation. Electrons from NADH and FADH2 are transferred through a series of electron carrier molecules in the inner mitochondrial membrane.
As electrons are passed along the chain, energy is released which is used to pump hydrogen ions across the membrane, creating a gradient. This gradient powers the enzyme ATP synthase that synthesizes ATP by adding a phosphate group to ADP in a process known as chemiosmosis.