Final answer:
When parking downhill, turn the vehicle's wheels to the right to prevent it from rolling into traffic; always engage the parking brake for safety. The correct answer is option a. The vehicle's wheels should be turned to the right.
Step-by-step explanation:
When parking a vehicle facing downhill, the correct procedure is to turn the vehicle's wheels to the right (option a). This ensures that if the vehicle were to roll, it would roll into the curb or roadside, lessening the chance of it rolling into traffic. When facing uphill with a curb, you should turn the wheels to the left.
Without a curb on an incline, always turn the wheels to the right. Make sure to engage the parking brake as well. This is done to prevent the vehicle from rolling into traffic in case the parking brake fails. When the wheels are turned to the right, the vehicle will roll into the curb or onto the side of the road, reducing the risk of accidents. Therefore, the correct answer is option a. The vehicle's wheels should be turned to the right.