A person travels from his house to his office by scooter at a speed of 40 km per hour. While returning, he travels at a speed of 20 km per hour. If the distance from his house to office is 5 km, what is his average speed of travelling both ways:

A) 30 km per hour

B) 25 km per hour

C) 26 * 2/3 km per hour

D) 30 * 1/3 km per hour

This MCQ is part of the UP PSC Previous Year Questions (PYQs) series, focusing on UPPSC Prelims 2002 (GS Paper I)