The correct option is B Floating respiration
Floating respiration uses carbohydrates or fats as the substrate for respiration. Since carbohydrates are the most preferred substrates for respiration, floating respiration is the most common mode of respiration.
Protoplasmic respiration uses proteins as the substrate for respiration. Since proteins are very rarely used as respiratory substrate, protoplasmic respiration is the rare mode of respiration.
Fermentation is the chemical breakdown of substrates (glucose) in the absence of oxygen.