Final answer:
Overpasses usually have a 16.5 foot clearance.
Step-by-step explanation:
The correct answer is c. 16.5 feet. Overpasses usually have a standardized minimum clearance to ensure that vehicles can safely pass underneath. This clearance is typically measured from the road surface to the bottom of the overpass bridge structure. A common clearance height for overpasses is around 16.5 feet, although it can vary depending on factors such as local regulations and infrastructure design.