What is one of the primary characteristics of bourbon whiskey?

One of the primary characteristics of bourbon whiskey is that it must be made from at least 51% corn. This grain composition is essential for the spirit's classification as bourbon, as it significantly influences the flavor profile, giving bourbon its characteristic sweetness and rich body. The law mandates that bourbon must also be distilled to no more than 160 proof and aged in new charred oak barrels to meet the legal definition, but the corn requirement is foundational to its identity.

The other options do not align with the established regulations governing bourbon. For instance, while aging bourbon contributes to its complexity, there is no minimum aging requirement of ten years; it simply needs to be aged in new charred oak barrels. Bourbon is a distinctly American spirit and cannot be produced in Scotland, as Scotland is known for Scotch whisky. Lastly, while bourbon can contain rye in the mash bill, it must contain at least 51% corn; it is not required to be devoid of rye.