Balance in account cannot be less than
With what do you need help with??
3.0 x 10^8 km/s is how far light travels.
3.0 x 10^8 km/s x 60s is how far light travels in a minute
3.0 x 10^8 x 60 x 5 is how far light travels in 5 minutes, and you should get D as your answer.
