What should you do at a red stop sign?

Answer: A — Stop

At a red stop sign, you are required to come to a complete stop before proceeding. Option B is incorrect because "yield" means to slow down and give the right-of-way to traffic or pedestrians, but not fully stop. Option C is incorrect because it goes against the purpose of a stop sign, which is to control traffic flow and ensure safety. Option D is incorrect because it suggests breaking the traffic law and making an illegal turn. To summarize, the correct action to take at a red stop sign is to come to a complete stop.