Which of the following is NOT one of the primary grains used in whiskey production?

The primary grains used in whiskey production typically include barley, corn, and rye, as they significantly contribute to the flavor profile and fermentation process in whiskey making. Barley is crucial, especially in Scotch and some Irish whiskies, as it can be malted to produce sugars necessary for fermentation. Corn is predominant in American whiskeys, particularly bourbon, where it must comprise at least 51% of the grain mix. Rye adds a spicy character and is utilized in both American rye whiskey and Canadian whiskies.

Rice, while a staple grain in many cultures for producing spirits, does not hold a common place in whiskey production. It is more often associated with the production of sake in Japanese and other Asian traditions. As such, rice is not classified among the primary grains employed in whiskey-making processes, making it the correct answer to the question.