**Concept:** **The question tests on the basics of Rates(Time Speed)**

**Solution:**

Pipe A fills in 12 hours, Pipe B takes 1.5 the time = 1.5 * 12 = 18 hours and Pipe C empties in 36 hours

The LCM of 12, 18 and 36 = 36

Pipe A can fill 36/12 = 3 units in 1 hour. So in 6 hours it fills 18 units

Pipe B can fill 36/18 = 2 units in 1 hour. So in 4 hours it fill 8 units.

Pipe C can empty 36/36 = 1 unit in 1 hour. In 6 hours it empties 6 units.

Net amount filled in 6 hours = 18 + 8 - 6 = 20 units

The remaining to be filled = 16 units

Pipe A and B in 1 hour fill 5 units. To fill 16 units they need 16/5 = 3.2 hours = 3 hours and 12 minutes.

Total time taken = 6 + 3 hours 12 minutes = 9 hours 12 minutes.

Option C