Why do we rely on lactic acid fermentation only as a temporary energy source?

This usually happens when there is not enough oxygen in the body, so lactic acid fermentation provides a way to get ATP without it. The process relies on stored energy sources such as sugars or starches, which it can break down to make simpler molecules and energy. ... Lactic acidosis usually occurs because of exercise.

answer; i believe that the correct answer is (lung);

i think that c)gold was found there

but i am not sure