Which of the following is not a type of white wine?

Merlot is not a type of white wine; it is classified as a red wine. This classification is due to the grape variety itself used to produce Merlot, which has a dark skin that contributes to the wine's characteristic color. White wines, on the other hand, are primarily made from green or yellowish grapes, which do not have the dark pigmentation associated with red wine grapes. The other options—Chablis, Chardonnay, and Pinot Grigio—are all types of white wine. Chablis is made from Chardonnay grapes and is known for its dry, crisp attributes. Chardonnay is a versatile white grape variety that can produce a range of wine styles. Pinot Grigio, known for being light and refreshing, is another popular white wine variety.