Which chemical classification is used for effective hazard communication internationally?

The Globally Harmonized System (GHS) is the correct choice because it is a comprehensive framework designed to standardize and improve the classification and labeling of chemicals worldwide. The GHS aims to ensure that information about chemical hazards is consistent and easily understandable across different countries and industries. This system provides a common language for identifying hazards and using appropriate hazard communication elements such as labels and safety data sheets.

By utilizing the GHS, organizations can facilitate safer handling, transport, and use of chemicals through clear communication of hazards, which ultimately helps protect workers, the public, and the environment. This effectiveness in hazard communication is crucial in a globally interconnected economy where chemicals may cross multiple borders. Other options, while potentially relevant to specific local or national contexts, do not provide the same level of international standardization and effectiveness in communicating chemical hazards.