A centrifugal pump is to discharge 0.118 m3/s at a speed of 1450 rpm against a head of 25m. The impeller diameter is 25cm, its width at outlet is 5 cm and manometric efficiency is 75%. The vane angle at outer periphery of impeller is
(a) 56.770 (b) 59.770
(c) 61.770 (d) 48.770