When a converging–diverging nozzle is operated at off–design conditions, a normal shock forms in the diverging portion. The nozzle can be assumed to be perfectly insulated from the surroundings. Then across the shock
(A) The velocity undergoes a jump but pressure and entropy remain unchanged
(B) The pressure undergoes a jump but velocity and entropy remain unchanged
(C) The velocity and pressure undergo a jump, but entropy remains unchanged because there is no heat transfer
(D) Velocity, pressure and entropy all undergo a jump