Which of the following is an example of a fortified wine?

The correct choice is sherry, as it is a well-known example of a fortified wine. Fortified wines are those to which a distilled spirit, usually brandy, has been added to increase their alcohol content. This process not only raises the alcohol level but can also influence the flavor profile of the wine, often giving it a richer and more complex taste.

Sherry, which originates from the Jerez region of Spain, is made from white grapes and undergoes a unique aging process that includes the addition of grapes that have been fortified with brandy. This contributes to its distinctive character, making it different from standard table wines or sparkling wines like Champagne.

Other choices do not fit the definition of fortified wines. For instance, Champagne is a sparkling wine that undergoes a different fermentation process, liqueurs are sweetened spirits with added flavors but are not classified as wines, and table wine typically contains no added spirits and falls within a standard alcohol content range without fortification.