Answer:
The correct answer is option c, that is, lactic acid.
Explanation:
One can determine the anaerobic function of muscles by observing the levels of lactic acid buildup in muscles. The production of lactic acid in muscles takes place by the process of anaerobic respiration. At the time of rigorous training or exercise, one requires more amount of energy for a short burst of time.
As oxygen is already used for higher purposes in the body, the levels of oxygen get reduced for performing any more activities. Thus, in order to generate more energy the process of anaerobic respiration takes place. Anaerobic respiration is the form of respiration that takes place in the absence of oxygen. In the process, one molecule of glucose gets transformed into two molecules of lactic acid, which gets accumulated in the muscles. This production of lactic acid provides a quick form of energy, which is utilized at the time of intense training and thus, one can check the anaerobic functioning of the muscles by observing the levels of lactic acid in the muscles.