Pipe A can fill the tank in 6 hours, pipe B can fill the tank in 10 hours and pipe C can empty the tank in 5 hours. The first two pipes are kept open for 3 hours in the begining and then the third pipe is also opened. In what time is the tank full?

• A. 5 hours
• B. 6 hours
• C. 8 hours
• D. 10 hours