What is one of the limitations for winemakers under the AOC system?

The answer regarding the limitations for winemakers under the AOC system is accurate because one of the fundamental aspects of the AOC (Appellation d'Origine Contrôlée) system is the strict adherence to specific regulations that dictate various factors related to wine production. These regulations often include the permissible grape varieties, vineyard practices, and blend compositions that are allowed for a particular appellation.

By requiring winemakers to follow detailed guidelines on blend compositions, the AOC system helps maintain the quality and character of wines that represent particular regions, ensuring consistency and authenticity. This commitment to specific blending rules is what reinforces the identity and reputation of a wine's origin.

The other potential options, while they might touch upon aspects of the winemaking process or regulations, do not accurately reflect the central limitations imposed by the AOC system in the same way that adherence to specific blend compositions does. This focus ensures that the unique terroir characteristics of the wines are preserved and celebrated, as intended by the AOC regulations.