B. 210 seconds
Feedback Since A beats B by 60 seconds and B beats C by 30 seconds. So, A beats C by 90 seconds.
But, it being given that A beats C by 375 metres. So it means that Covers 375 metres in 90 seconds.
Time taken by C to cover 1 km =90/375×1000 seconds= 240 seconds
Time taken by A to cover 1 km = (240-90) seconds = 150 seconds
Time taken by B to cover 1 km = (240-30) seconds= 210 seconds.