A tap can fill up a tank of 1250 litres in 4 hours, whereas another tap can fill the same tank in 8 hours. An outlet tap can empty that tank in 6 hours.If all the three taps are opened simultaneously, then how much time will it take to fill the tank completely?

A

4.2 hours

B

5 hours

C

4.5 hours

D

4.8 hours