Yeast Produce Ethanol,a Toxic Waste Product,during Fermentation

Yeast produce ethanol,a toxic waste product,during fermentation.Why would yeast produce something that is toxic to themselves?

A) to use up excess pyruvate in order to continue glycolysis
B) to conserve oxygen for other reactions
C) to regenerate NAD⁺ in order to continue glycolysis
D) to avoid the production of lactic acid
E) to produce NADH for energy