Three pipes A, B and C can fill a tank in 10, 15 and 20 hours respectively. Pipe A was opened at 6 AM, pipe B at 7 AM and pipe C at 8 AM. At what time was the tank completely filled, if pipe C needs a break of 1 hour after remaining open for 3 hours?

A

11:20 AM

B

12:30 PM

C

11:30 AM

D

12:15 PM