What is the main aging characteristic of a fino sherry compared to an oloroso?

Fino sherries are characterized primarily by their aging process, which involves the presence of a natural layer of yeast known as "flor." This flor forms on the surface of the wine while it is aging, protecting it from oxidation and imparting unique flavors and aromas. The biological aging under flor contributes to the lighter, more delicate profile of fino sherry, making it distinct from oloroso sherry, which is oxidatively aged without flor. As a result, oloroso sherries tend to have a richer, darker profile with more robust flavors, while fino sherries exhibit crispness and freshness due to their aging method.

The other choices do not accurately reflect the key differences between the two types of sherry. For instance, fino sherries are generally not sweeter than olorosos; rather, they are typically dry. Additionally, fino sherries usually have a lower alcohol content compared to olorosos, which are fortified to a higher level. Lastly, while pricing can vary based on numerous factors, there is no strict rule that makes fino sherries always pricier than olorosos. Hence, the primary distinction lies in the biological aging process that defines the fino style.