Answer:
b. reactions in the electron transport chain
Explanation:
Oxidative phosphorylation, which is the process described in this question, is the third stage of cellular respiration which occurs in the MITOCHONDRION of eukaryotic cells. In this stage of oxidative phosphorylation, which encompasses electron transport chain (ETC) and chemiosmosis, ATP is synthesized.
The ATP is synthesized when protons (H+) move from the mitochondrial matrix into the intermembrane space, forming, a proton pump. The series of electron transfers (reactions) that occur in the complexes of the ETC provides the ENERGY to pump the protons/hydrogen ions out of the matrix, which creates the electrochemical gradient required for ATP synthesis with the help of ATP synthase.
