Final answer:
The posted speed limit is the maximum legal speed you can travel on that road, and the answer to the student's question is True. The de facto speed limit might differ, but adherence to the posted limit is recommended.
Step-by-step explanation:
The speed limit indicated on a sign is indeed the maximum legal speed at which you can travel on that road under ideal conditions. The answer to the student's question is True. However, it is important to note that the de facto speed limit may be different, which refers to the speed at which law enforcement may actually decide to pull you over
This can sometimes be a bit higher than the posted speed limit, depending on local enforcement practices. However, the safest and most lawful choice is to adhere strictly to the posted speed limit.