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 = Vo

B. Vt > Vo

C. U < Vo

D. V = Uo

Please do not use chat terms. Example: avoid using "grt" instead of "great".