This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Metabolism of carbohydrate, Subject name: Biochemistry
Hydrogen ions are not formed by which complex or which is not a proton pump? 
Select and explain. 
A. Complex I, B. Complex II, C. Complex III, D. Complex IV
B: Complex II
Answer: B: Complex II 
Explanation: Complex II or Succinate-Q-reductase; the electrons from FADH2 enter the ETC at the level of coenzyme Q. This step does not liberate enough energy to act as a proton pump.(fig.20.13)Ref: DM Vasudevan, 7th edition, page no: 261