Which ingredient is used to filter Tennessee whiskey?

The correct answer is that coal saturated in maple syrup is used to filter Tennessee whiskey, a specific process known as the Lincoln County Process. This method involves passing the spirit through a bed of charcoal made from sugar maple trees, which not only helps to cleanse the whiskey of impurities but also enhances its flavor profile by imparting subtle sweetness. This unique filtration method is a defining characteristic of Tennessee whiskey, setting it apart from other types of whiskey, such as bourbon.

The other options do not represent actual practices used in the production of Tennessee whiskey. Activated charcoal is commonly used in various filtration processes and might be familiar to many, but it is not specifically linked to Tennessee whiskey production. Oak chips are sometimes used in winemaking and other spirits to add flavor and complexity, but they do not serve as a filtering agent. Lastly, clay filters are not a traditional element of whiskey production, making the chosen method of coal saturated in maple syrup the distinctive and correct answer.