A pipe can fill a tank in 16 minutes and a second one in 24 minutes. A third pipe cnn empty that full tank in 8 minutes. The first 2 pipes are kept open for 4 minutes in the beginning and then the third pipe is also opened. Then the time (in minutes) in which the tank will be emptied after all the three pipes started working simultaneously.

A

30

B

20

C

26

D

24