What is the minimum speed limit on expressways and freeways?

Answer: D — 35 mph

On expressways and freeways, the minimum speed limit is typically 35 mph. Option A is incorrect because 25 mph is typically the minimum speed limit on residential streets. Option B of 15 mph is much too slow for a high-speed roadway such as an expressway or freeway. Option C of 45 mph is actually closer to the average speed limit on these types of roads, not the minimum. Therefore, D is the correct answer as it is the most accurate and reasonable option for the minimum speed limit on expressways and freeways.