Cells produce energy by breaking down sugar and other molecules in the presence of oxygen to produce ATP. So the answer is "B".
Explanation:
The process of producing ATP in animal cells occurs through cellular respiration. Various processes occur in this which involve the presence or absence of oxygen. Glycolysis in the presence of oxygen leads to the production of two molecules of ATP. Glucose is broken down into pyruvate and water.
In citric acid cycle, acetyl coA is utilized to produce <u>2ATP, 6NADH and 2FADH molecules.</u>
Finally oxidative phosphorylation occurs in mitochondria. With the help of electron transport chain, ATP is synthesized by ATP synthase enzyme.
