Which of the following is a common characteristic of high-acid grape varieties?

High-acid grape varieties are often characterized by their fresh and crisp taste, which is a result of elevated acidity levels in the fruit. This acidity contributes to a lively, refreshing quality in the wine, enhancing the overall flavor profile and making it more vibrant on the palate. It can also aid in food pairing, as the bright acidity can complement rich or fatty dishes effectively.

In contrast to this, while some grapes might exhibit low sugar content, that is not universally applicable. Additionally, high sweetness is typically associated with grapes that have higher sugar concentrations, not those with high acidity. Heavy tannins are more commonly found in red grape varieties, particularly those with thicker skins, and are not characteristic of high-acid varieties, which are more likely to be lighter-bodied and, in many cases, white or fruit-forward reds. Therefore, the fresh and crisp taste is a defining trait of high-acid grape varieties.