In case of laminar flow of fluid through a circular pipe, the

• A. Shear stress over the cross-section is proportional to the distance from the surface of the pipe
• B. Surface of velocity distribution is a paraboloid of revolution, whose volume equals half the volume of circumscribing cylinder
• C. Velocity profile varies hyperbolically and the shear stress remains constant over the cross-section
• D. Average flow occurs at a radial distance of 0.5 r from the centre of the pipe (r = pipe radius)