A yeast cell feeding on glucose suddenly switches from producing carbon dioxide and many ATP molecules to producing ethyl alcohol and few ATP molecules which of the following would force to yeast to make this change

There are two types of fermentation carried out here and are also defined by the types of products generated at the end of the process. During aerobic fermentation, Co2 and ATP are produced while when air is not present, metabolites such as ethyl alcohol and few ATP are generated. The answer is shift from aerobic to anaerobic environment.