Which wine is typically known for its high residual sugar content?

Port is typically known for its high residual sugar content due to the winemaking process it undergoes. It is a fortified wine, which means that during fermentation, grape spirits are added to the wine, halting fermentation before all the sugar has been converted into alcohol. This technique preserves some of the natural sugar from the grapes, resulting in a sweet taste profile.

Additionally, Port is often made from grape varieties such as Touriga Nacional and Tinta Roriz, which can contribute to its rich, sweet flavors. The sweetness, combined with the higher alcohol content from fortification, defines Port's characteristic profile, making it a popular choice for dessert pairings.

In contrast, the other options typically have much lower levels of residual sugar. Vermentino is a dry white wine with crisp acidity, Chianti is primarily dry with moderate tannins and bright acidity, and Sauvignon Blanc is usually fermented to a dry style, although it can vary slightly depending on the producer but generally does not reach the high sugar levels characteristic of Port.