What should a driver do when approaching a railroad crossing?

Answer: D — educe speed and look in both directions

When approaching a railroad crossing, a driver should reduce their speed and look in both directions to ensure that no trains are coming. Option A is incorrect because simply looking up and down the tracks does not guarantee that no trains are coming. One should also look in both directions of the tracks. Option B is incorrect because speeding up can be dangerous and potentially result in a collision with an oncoming train. Option C is incorrect because ignoring the signs and crossing immediately can lead to a serious accident or even death. Therefore, reducing speed and looking in both directions is the safest and most responsible action a driver can take when approaching a railroad crossing.