If V, U and Vr represent the absolute velocity of fluid, velocity of blade, and relative velocity of fluid, and suffix i and o stand for entry and exit conditions, then in a rotary machine whose degree of reaction is unity______________?
(A) Vi=V0B
(B) Vt>V0
(C) U,<V0
(D) V,= U0
(E) Vri=Vm

