A bus travels at a speed of 50 km per hour to go from its origin to its destination at a distance of 300 km and travels at a speed of 60 km per hour to return to the origin. What is the average speed of the bus ?

• A. 54.55 km per hour
• B. 55 km per hour
• C. 55.55 km per hour
• D. 54 km per hour