A hungry yeast cell lands in a vat of grape juice and begins to feast on the sugars there, producing carbon dioxide and ethanol in the process:

C6H12O6 + 2ADP + 2Pi + H+ → 2CO2 + 2CH3CH2OH + 2ATP + 2H2O

Unfortunately, the grape juice is contaminated with proteases that attack some of the transport proteins in the yeast cell membrane, and the yeast cell dies. Which of the following is the most likely cause of the yeast cell’s demise?

a. toxic buildup of carbon dioxide inside the cell
b. toxic buildup of ethanol inside the cell
c. diffusion of ATP out of the cell
d. inability to import sugar into the cell
e. inability to take water into the cell