Final answer:
In the U.S., a wine must contain at least 75% of a grape variety to be labeled as that varietal, like Chardonnay.
Step-by-step explanation:
In the United States, for a bottle of wine to be labeled as a specific varietal, such as Chardonnay, the bottle must contain at least 75% of that grape variety. This requirement allows a small percentage of other grape varieties to be blended in if so desired by the winemaker, yet still maintains the dominant characteristics of the varietal named on the label. Different countries may have their own standards, but for U.S. wines, the 75% threshold applies.