Final answer:
Option 1. is correct. When transitioning from hard pavement to an earthen road, it is essential to slow down to maintain control of the vehicle, since the change in surface affects traction and the vehicle's handling dynamics.
Step-by-step explanation:
When the hard pavement you are traveling on is about to change to an earthen road or lower surface, the proper action to take is to slow down to maintain control of your vehicle. This approach helps manage the transition from a smooth to a potentially more uneven and loose surface, which can affect traction and stability. Speeding up or ignoring the change would increase the risk of losing control or damaging the vehicle. Considering road safety practices and vehicle dynamics, maintaining a consistent and appropriate speed is crucial, especially during such transitions.
These principles are supported by the physics of motion, where the friction between the tires and road surface impacts the car's handling. Changing from a hard pavement to an earthen road alters the frictional force, thereby influencing the vehicle's ability to brake and maneuver. Consequently, as the friction decreases on softer or more irregular surfaces, it becomes imperative for the driver to adjust speed accordingly to remain safe.