AIIMS 2019 Zoology Muscle Contraction MCQ Question

During vigorous exercise, when oxygen availability is limited, cells switch to anaerobic respiration, where pyruvic acid is converted to lactic acid to generate ATP without oxygen. This process allows for continued energy production in the absence of sufficient O₂, making option B (Anaerobic respiration) the correct choice. Option A (Aerobic respiration) is incorrect because it requires oxygen to produce energy efficiently. Option C (Fermentation) is a broader term that includes anaerobic processes like lactic acid fermentation, while option D (Glycolysis) refers specifically to the initial breakdown of glucose into pyruvate, which occurs before either aerobic or anaerobic pathways.