C.

If a wine has any natural grape sugar left—that is, if some of the sugar was not converted to alcohol during fermentation—then the wine is said to have residual sugar. In order to be considered a sweet wine (not a table wine), a wine has to have quite a lot of unconverted natural grape sugar. According to European Union legislation, for example, a wine labeled “sweet” must have at least 4.5% residual sugar. Most of Europe’s great sweet wines, however, have considerably more than that. Port, Sauternes, and German TBAs are all sweet, but nothing compares to Spain’s opulent Pedro Ximénez Sherries (PX), which can have over 40% residual sugar. PX wines are nearly black in color and have a texture as thick as maple syrup. A small glass is more than dessert wine, it is dessert.