Pick out the wrong statement ?

A. The vessel dispersion number (D/UL) for plug flow and mixed flow approaches zero and
infinity respectively
B. Space time in a flow reactor is a measure of its capacity and is equal to the residence time when the density of reaction mixture is constant
C. Mixed reactor is always smaller than the plug flow reactor for all positive reaction orders for a
particular duty
D. In an ideal tubular flow reactor, mixing takes place in radial direction and there is no mixing in longitudinal direction