The correct answer is (a) during production of wine from grapes.
The equation for alcoholic fermentation of glucose is :
Glucose (C6H12O6) → 2 Ethanol (C2H5OH) + 2 Carbon Dioxide (CO2) + Energy
In the absence of oxygen, yeast or other microorganisms carry out this process. Wine is created during the wine-making process when yeast transforms the natural sugar found in grapes into ethanol and carbon dioxide.