The correct option is
D Fermentation
The process of fermentation is the form of anaerobic respiration carried by some microorganisms. Many microorganisms such as fungus and bacteria can grow and flourish in the complete absence of oxygen. Such microorganisms can utilize sugars to convert it into ethanol and evolve carbon dioxide. Since it is the incomplete breakdown of glucose, it yields small amount of energy which is sufficient to maintain the life of organisms like yeast and bacteria.
Thus, the correct answer is 'Fermentation'.