What should you do if red lights are flashing at a level crossing?

Answer: C — Stop before the barrier

When red lights are flashing at a level crossing, it is indicating that a train is approaching and you must come to a complete stop before the barrier to let the train pass. Option A is incorrect as you should not continue with caution, you must stop. Option B is partially correct, but it is not enough to just stop if you can do so safely, you must make sure to stop before the barrier. Option D is incorrect as accelerating to clear the crossing can put you and others in danger. Therefore, the best and safest option is to stop before the barrier when red lights are flashing at a level crossing.