A pressurized cylindrical tank, 5.0 {\rm m} in diameter, contains water which emerges from the pipe at point C, with a velocity of 12 {\rm m/s}. Point A is 10 {\rm m} above point B and point C is 3 {\rm m} above point B. The area of the pipe at point B is 9×10?2 {\rm m}^{{2}} and the pipe narrows to an area of 2×10?2 {\rm m}^{{2}} at point C. Assume the water is an ideal fluid in laminar flow. The density of water is 1000 {\rm kg/m}^{{3}}. In the figure, the rate at which the water level is falling in the tank, in \rm mm/s, is closest to: