Which of the following is true about bottle-conditioned beer?

Bottle-conditioned beer undergoes a secondary fermentation in the bottle, which is the defining characteristic of this style. This process typically involves adding a small amount of sugar and yeast before sealing the bottle. As the yeast consumes the sugar, it produces carbon dioxide and a small amount of alcohol, resulting in natural carbonation. This method not only creates a livelier mouthfeel but also contributes to complex flavors as the beer matures in the bottle.

While bottle-conditioning can enhance shelf life, it does not automatically guarantee a longer shelf life than other types of beers, which is why that choice is not correct. Additionally, bottle-conditioned beers are generally not pasteurized before bottling, as pasteurization would kill the yeast needed for secondary fermentation, thus negating the benefits of the bottle-conditioning process. Lastly, once a bottle is opened, the level of carbonation can decrease, but this does not mean that the beer cannot be re-carbonated; it simply won’t retain the same natural carbonation as it had before being opened.