NEET Biology question

Though vertebrates are aerobes, their (i) show anaerobic respiration during (ii). During this, (iii) of skeletal muscle fibres is broken down to release lactic acid and energy. Lactic acid, if it accumulates, causes muscle fatigue. Fill in the blanks in the above paragraph and select the correct option.

• (A)(i) skeletal muscles, (ii) heavy exercise, (iii) glucoseCorrect
• (B)(i) skeletal muscles, (ii) mild exercise, (iii) glycogen
• (C)(i) skeletal muscles, (ii) heavy exercise, (iii) glycogen
• (D)(i) cardiac muscles, (ii) heavy exercise, (iii) glycogen