Which signs indicate the maximum legal speed in ideal conditions?

Answer: B — Speed limit signs

Speed limit signs tell you the maximum legal speed you may drive on that road under ideal conditions. They’re a regulatory sign, meaning they set a legal requirement for how fast you can travel. This is what makes them the right choice: speed limit signs specify the upper limit you must not exceed when conditions are good. Other signs serve different purposes—warning signs alert you to hazards or changes in the road ahead, guide signs provide directions or distances, and regulatory signs cover rules like stops or turns. If conditions aren’t ideal (rain, ice, construction), you should slow down even more, but the posted limit is the maximum permitted under ideal conditions.