Final answer:
Single grain whiskey must be produced at one distillery using any single grain along with yeast and water.
Step-by-step explanation:
In order to produce single grain whiskey, it must be produced at one distillery using any single grain. This means that single grain whiskey can be made from different types of grains, such as barley, corn, or wheat, but it must be produced at a single distillery. Single grain whiskey can also be made using other ingredients like yeast and water.