When A produces 400 kW at 1000 rpm. If B produces 100 kW, then its rpm is

Question

Two pelton wheels A and B have the same specific speed, and are working under, the same head. When A produces 400 kW at 1000 rpm. If B produces 100 kW, then its rpm is        

a. 4000                                    b. 2000

c. 1500                                    d. 1250