When should a driver obey the instruction of sign A3?

The correct answer indicates that a driver should obey the instruction of sign A3 only during adverse weather conditions. This sign typically relates to altering driving behavior when visibility is reduced or road conditions are unsafe due to factors like rain, fog, or snow. The intention behind this approach is to ensure safety on the road by encouraging drivers to remain vigilant and make necessary adjustments in their driving practices during such conditions, which are known to increase the risk of accidents.

In general driving conditions, the instruction may not be as critical, and drivers can follow normal driving rules. This focuses on the importance of situational awareness and adapting to environmental changes, which can significantly impact driving safety.