The correct option is C Glucose
Our muscle cells respire anaerobically for a short period during heavy exercises such as running or cycling. The demand for energy while performing these activities is quite high. And, since the supply of oxygen to produce the energy is limited, anaerobic respiration takes place in the muscle cells. The by-products are lactic acid and energy. Excess accumulation of lactic acid causes muscle cramps.
Glucose Absence of oxygen−−−−−−−−−−−→ Lactic acid+ Energy