Name a spirit that is made from fermented grains.

Whiskey is a spirit that is distinctly made from fermented grains, which typically include barley, corn, rye, and wheat. The process of making whiskey begins with mashing these grains and then fermenting the mash to convert the sugars into alcohol. It is then distilled and aged in wooden barrels, which contributes to its characteristic flavor and color.

Vodka, while it can be made from grains, is often distilled to a higher proof and can also be produced from potatoes or other ingredients, focusing more on purity and neutrality rather than the flavors derived from grains. Rum, on the other hand, is made from sugarcane or molasses, which sets it apart entirely from grain-based spirits. Tequila is made specifically from the blue agave plant and is unique to Mexico. Thus, whiskey is the correct answer as it specifically originates from fermented grains and has its own established production methods and flavor profile.