Answer: option D is the correct answer.
Step-by-step explanation:
The first part of the race was 15 km long, and he completed it in 1 hour.
Speed = distance/time
Therefore, John's speed in the first part of the race would be
15/1 = 15km/hr
The second part was 18 km long, and he completed this part in an hour and a half. This means that his speed in the second part of the race is
18/1.5 = 12km/hr
Total distance/total time
Total distance for both parts of the race is 15 + 18 = 33km
Total time for the race is 1 + 1.5 = 2.5 hours
John's average speed for the whole race would be
33/2.5 = 13.2 kilometers per hour
