Answer the following question given this paragraph: 

Brewers of beer and wine use yeast to add alcohol to beverages. Traditional varieties of yeast not only make but also limit the quantity of alcohol in these beverages, because above 18% by volume, alcohol becomes toxic to the yeast itself. Wine is produced by fermentation of the natural sugars present in grapes and other kinds of fruit. Beer, whiskey, and vodka are produced by fermentation of grain starches that have been converted to sugar by the enzyme amylase, and rum is produced by fermentation of sugarcane. In each of these fermentations, sugars are converted into small amounts of ATP, using and regenerating NAD + in the process, and producing ethanol and carbon dioxide. Scientists have recently developed new strains of yeast which can tolerate up to 25% alcohol by volume. These are used primarily in the production of ethanol fuel.


Q: Why do beer brewers add yeast to the wort?


A:
to make alcohol