What defines an international grid system in electricity distribution?

The choice that defines an international grid system in electricity distribution is the one that describes an electrical supply distribution network that allows cross-border electricity exchange. This reflects the purpose and functionality of international grids, which are designed to facilitate the transfer of electricity between different countries. Such systems enable nations to share resources, balance supply and demand, and improve the overall efficiency and reliability of electricity distribution.

International grids help in optimizing energy use, especially in regions where renewable energy sources are prevalent, as they can transmit surplus energy generated in one country to another that may need it. Moreover, it allows countries to take advantage of varying energy prices and resources, leading to economic benefits and enhanced energy security.

On the other hand, the other options focus on localized or restricted systems that do not encourage cross-border electricity exchanges, thus missing the essential characteristic of an international grid system. They emphasize nationalistic approaches to electricity distribution rather than the collaborative and interdependent nature of international electricity networks.