Sometimes there is not enough oxygen in a cell for cellular respiration to occur. In this case, the cell may use the process of fermentation to get the energy it needs in order to carry out cellular processes. Fermentation is the breakdown of organic compounds in the absence of oxygen. The byproducts of fermentation differ from cellular respiration.

Which of the following is a chemical byproduct of fermentation in humans?
A.
pyruvate
B.
glucose
C.
ADP
D.
lactic acid