A five day B.O.D. at 15°C of the sewage of a town is 100 kg/day. If the 5 day B.O.D. per head at 15°C for standard sewage is 0.1 kg/day, the population equivalent is____________________?

A. the direction and magnitude of the velocity at all points are identical
B. the velocity of successive fluid par-ticles, at any point, is the same at suc-cessive periods of time
C. the magnitude aricf direction of the velocity do not change from point to point in the fluid
D. the fluid particles move in plane or parallel planes and the streamline pat-terns are identical in each plane
E. velocity, depth, pressure, etc. change from point to point in the fluid flow

A. only when the fluid is frictionless
B. only when the fluid is incompressible and has zero viscosity
C. when there is no motion of one fluid layer relative to an adjacent layer
D. irrespective of the motion of one fluid layer relative to an adjacent layer
E. in case of an ideal fluid