What is the maximum speed limit when operating a school bus on a rural interstate highway?

Answer: C — 55 miles per hour

When operating a school bus on a rural interstate highway, the maximum speed limit is 55 miles per hour. This speed limit ensures the safety of the students on board as well as other drivers on the road. It is important for school bus drivers to adhere to this speed limit to maintain a safe environment for everyone. The other options (45, 50, and 60 miles per hour) are not applicable as they exceed the maximum speed limit allowed for a school bus on a rural interstate highway in Indiana.