The correct answer is option 3. removal of hydrogen atoms from lactic acid.
Explanation:
In anaerobic conditions, it ferments to generate lactic acid. It is two way or reversible process in which oxidation of lactic acid produces pyruvic acid and NADH.
This process involves the removal of hydrogen atoms from the lactic acid and produces NADH and H⁺ in the presence of lactate dehydrogenase enzyme and convert into pyruvic acid.
Thus, the correct answer is option 3. removal of the hydrogen atoms from lactic acid.
Larger organism increases more in volume than area. That's why larger organism uses respiratory systems or organs and systems instead of simple diffusion for removal of waste and absorption of nutrients.