Final answer:
To park safely downhill on a two-way road, the driver should turn the vehicle's wheels toward the curb and engage the parking brake firmly.
Step-by-step explanation:
When parking downhill on a two-way road, it is important for a driver to take certain safety precautions to prevent the vehicle from rolling into traffic. The correct technique is to turn the vehicle's wheels toward the curb or side of the road. This way, if the brakes were to fail, the vehicle would roll into the curb and stop, rather than rolling into the traffic lane. Additionally, the driver should engage the parking brake firmly to secure the vehicle.