This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Biochemistry
In ETC, oxidative phosphylartion (ATP formation) is regulated by 
Select and explain. 
A. NADH Co-Q reductase, B. Cytochrome C oxidase, C. Co-Q cytochrome C reductase, D. All of these
D: All of these
Answer: D: All of these 
Explanation: NADH Co-Q reductase; 'b' i.e., Cytochrome C oxidase & `e' i.e., Co-Q cytochrome C reductase