A U-tube manometer with a small quantity of mercury is used to measure the static pressure difference between two locations A and B in a conical section through which an incompressible fluid flows. At a particular flow rate, the mercury column appears as shown in the figure. The density of mercury is 13600 kg/m^3 and g = 9.81 m/s^2. Which of the following is correct?
A. Flow direction is A to B & PA−PB = 20 kPa B. Flow direction is B to A & PA−PB = 1.4 kPa C. Flow direction is A to B & PB−PA = 20 kPa D. Flow direction is B to A & PB−PA = 1.4 kPa