Water flows through a vertical contraction from a pipe of diameter d to another of diameter d/2 (see Figure). The flow velocity at the inlet to the contraction is 2 m/s and the pressure is 200 kN/m2. If the height of the contraction measures 2m, then the pressure at the exit of the contraction will be very nearly

A. 168 kN/m^2 B. 192 kN/m^2 C. 150 kN/m^2 D. 174 kN/m^2