What classification applies to vines that are at least 100 years old?

The classification that applies to vines that are at least 100 years old is referred to as "Centurian." This term is specifically utilized in the wine industry to denote very old vines, generally indicating not just the age but also the potential for unique characteristics and quality in the wine produced from such vines. Vines of this age often yield lower quantities of grapes, which can lead to more concentrated flavors.

The other options may refer to different concepts or classifications in the context of viticulture or grapevine age, but they do not specifically encapsulate the idea of a vine reaching the significant milestone of 100 years. "Old Vine" typically denotes vines that are older than a certain age, often around 30 years or more, but it is not limited to those that reach the century mark. "Ancestor" and "Survivor" may imply longevity or resilience, but they are not recognized industry classifications for vines that are 100 years old. Thus, "Centurian" is the correct term for vines of this venerable age.