Which of the following is NOT a common type of whiskey?

Tequila is the correct choice because it is a distinct type of spirit made primarily from the blue agave plant, primarily produced in specific regions of Mexico. It is not related to whiskey, which is produced from fermented grain mash that may include barley, corn, rye, and wheat.

On the other hand, bourbon, scotch, and Irish whiskey are all recognized styles of whiskey. Bourbon is typically made in the United States and is known for its sweet flavor derived from a corn base. Scotch is a whisky (note the absence of the "e") that comes exclusively from Scotland and is known for its distinct flavors resulting from malted barley and specific aging processes. Irish whiskey, produced in Ireland, is known for its smoothness and is usually triple distilled.

In summary, while bourbon, scotch, and Irish represent traditional types of whiskey, tequila stands apart as an entirely different category of alcohol.