C. To make pyruvate in the cytoplasm
During both cellular respiration and fermentation, glucose is used to make pyruvate in the cytoplasm of the cell. This process is known as glycolysis. In glycolysis, glucose is broken down into pyruvate, producing a small amount of ATP and electron carriers (NADH).
After glycolysis, the fate of pyruvate differs between cellular respiration and fermentation. In cellular respiration, pyruvate enters the mitochondria where it undergoes further breakdown to produce more ATP through processes like the Krebs cycle and oxidative phosphorylation. In fermentation, pyruvate is further metabolized in the cytoplasm to produce products like ethanol or lactic acid, depending on the organism and the type of fermentation.
Therefore, option C is the correct statement regarding the use of glucose in both cellular respiration and fermentation.