The correct option is
B Anaerobic respiration
Anaerobic respiration is the respiration which takes place in the absence of oxygen. It is also known as fermentation. It takes place in the unicellular organisms. It leads to production of two ATP. Respiratory quotient is the ratio of volume of carbon dioxide produced to volume of oxygen consumed.
In anaerobic respiration no oxygen is required. i.e., it occurs in the absence of oxygen and so, the RQ is infinity.So, the correct answer is option B.