Task: Question Answering
Input (English): Question: The conversion of pyruvate into ethanol and CO2 by yeasts: 
 Options:  <1> It produces an extra amount of ATP. <2> Reduce the NAD +. <3> Reoxidates the NADPH that forms in glycolysis. <4> It allows glycolysis to continue even in the absence of oxygen. <5> Allows CO2 to be used in the synthesis of fatty acids.
Output (English): 4