When you approach a railroad crossing and you see the crossing arms down, you must

Answer: C — stop and then proceed

When approaching a railroad crossing, it is important to always be cautious. The crossing arms being down is a sign that a train is approaching, so it is necessary to stop and wait for the train to pass before proceeding. Honking your horn or speeding up to try to get across is dangerous and can result in a collision with the train. It is important to always follow traffic signs and signals, especially when it comes to railroad crossings.