What is typically unique about a Lambic (unblended)?

A Lambic, specifically when referring to unblended varieties, is distinguished primarily by its spontaneous fermentation process. This means it is fermented using wild yeast and bacteria that are naturally present in the environment, rather than cultivated yeast strains. This unique fermentation method contributes several distinct characteristics to the beer, including complex flavors and aromas that are not typically found in beers made with standard fermentation practices.

The other aspects mentioned in the choices highlight characteristics that might be associated with certain beers but do not define Lambics in the same way. For example, while Lambics can be aged and may include fruit additions, these features are not exclusive to unblended Lambics and can vary widely among different styles within the category. Additionally, the hop character in Lambics is usually quite low, particularly compared to other beer styles, which tend to emphasize hop bitterness and aroma. Thus, the spontaneous fermentation is the key defining element that makes Lambic unique.