Biology helpp ? please and thank you !?

43. Lactic acid fermentation is one of the processes that supplies energy when oxygen is scarce. Two molecules of pyruvic acid produced in glycolysis use NADH to form two molecules of lactic acid. This releases NAD+ to be used in glycolysis, allowing two ATP molecules to be formed for each glycolysis molecule. The lactic acid is transferred from muscle cells, where it is produced during strenuous exercise, to the liver that converts it back to pyruvic acid.