A conical diffuser 3m long is placed vertically. The velocity at the top (entry) is 4 m/s and at the lower end is 2 m/s. The pressure head at the top is 2m of the oil flowing through the diffuser. The head loss in the diffuser is 0.4m of the oil. The pressure head at the exit is
(a) 3.18 of oil (b) 5.21 of oil
(c) 7.18 of oil (d) 9.21 of oil