Biology · Bioenergetics

Glycolysis, the first step of aerobic respiration, which results in the formation of two molecules of pyruvate from one molecule of glucose, occurs in the cytoplasm of the cell. 

'Nucleus' is not involved in any steps of respiration. It is the brain of the cell.

Option B mentions 'mitochondria', which is the site for the remaining steps of aerobic respiration; after pyruvate is made in the cytoplasm via glycolysis, it is shunted into the mitochondria where it is involved in the formation of acetyl CoA via the link reaction after which the Krebs Cycle takes place (link reaction and Krebs cycle occur in the mitochondrial matrix). Finally, the terminal reaction of aerobic respiration occurs across the inner mitochondrial membrane, which is oxidative phosphorylation.

Option C mentions the Golgi complex, which is not involved in any steps of respiration; it merely serves as the site of protein packaging and subsequent transport.

Glycolysis, the first step of aerobic respiration, results in the formation of two molecules of pyruvate from one molecule of glucose and occurs in the cytoplasm of the cell. Hence, option D is correct.