One pipe fills a water tank three times faster than another pipe. If the two pipes to-Other can fill the empty tank in 36 minutes, then how much time will the slower pipe alone take to fill the tank ?

• A. (1) 1 hour 21 minutes
• B. (2) 1 hour 48 minutes
• C. (3) 2 hours
• D. (4) 2 h,our 24 minutes