How long is the validity period of an ADR Certificate detailing a driver's training for transporting hazardous goods?

The validity period of an ADR Certificate, which certifies a driver's training for transporting hazardous goods, is set according to German and European regulations. The correct combination would include the main duration of validity, which is five years. After this period, drivers must undergo retraining to ensure they are up-to-date with safety measures and regulations related to hazardous goods transportation. This requirement is vital for maintaining high safety standards on the roads and ensuring that drivers are well-versed in handling these materials responsibly. It's essential to select the correct validity period to comply with the regulations effectively.