D. 125 m
Feedback A can give B a start of 15 seconds in a km race.
B takes 4 minutes to run a km. i.e 1000/4= 250 m/min = 250/60 m/sec
Therefore, B will cover a distance of = 62.5 meters in 15 seconds.
The start that A can give B in a km race therefore, is 62.5 meters, the distance that B run in 15 seconds.
Hence in a 2 km race, A can give B a start of 62.5 * 2 = 125 m or 30 seconds.