When may you pass another vehicle on the right?

Answer: A — When the other vehicle is turning left

Passing another vehicle on the right should only be done when it is safe to do so and should always be done with caution. Option B and C are incorrect as they both involve the other vehicle turning in the direction that you would be passing them, which can be dangerous and may result in a collision. Option D is incorrect because there are certain situations where it may be necessary to pass on the right, such as when the other vehicle is significantly slower than the flow of traffic on the left. Therefore, the safest and most correct option is A, passing on the right when the other vehicle is turning left. This ensures that both vehicles are moving in opposite directions and there is less risk of a collision.