On a single-lane roadway, you should pass vehicles:

Answer: C — Either left or right, depending on the situation

When passing vehicles on a single-lane roadway, you should do so with caution and consider the situation at hand. Passing on either side may be appropriate depending on factors such as visibility and oncoming traffic. Passing on the left is the most commonly followed rule, but there may be instances where it is safer to pass on the right side. Passing should only be done when it is safe to do so and when there is ample space to pass the vehicle. Therefore, option C is the correct answer as it best encompasses all possible situations on a single-lane roadway.