Glycolysis is an anaerobic process & takes place in cytosol, through which one glucose molecules is breakdown into two molecules of three-carbon pyruvate. The glycolysis of each glucose molecule generates 2 ATP molecules. ATP synthesis from anaerobic process is via glycolysis of glucose in the presence of various enzymes.
Glucose + 2 NAD+ + 2 Pi + 2 ADP → 2 pyruvate + 2 NADH + 2 ATP + 2 H+ + 2 H2O + heat
Citric acid cycle:
The pyruvate generated by the glycolysis is converted into acetyl-CoA that enters into the citric acid cycle. Citric acid cycle involves a series of reactions that occur in the presence of oxygen. Citric acid cycle generates NADH, which enters into the oxidative phosphorylation process. This cycle occurs in mitochondrial matrix and generates one ATP molecule only.
Thus, the options (b), (c) and (d) are incorrect.
Glycolysis is an initial anaerobic process & takes place in cytosol, through which one glucose molecules is breakdown into two molecules of three-carbon pyruvate.
Therefore, the correct option is – a. glycolysis.