Velocity of flow of water in pipes and tubes is explained by__________

Correct option is D

The William and Hazen equation, often referred to as the Hazen-Williams formula, is specifically designed to estimate the velocity of water flow in a pipe. This empirical formula is widely used in civil engineering and takes into account the roughness of the pipe's interior surface and the hydraulic gradient. While Darcy's Law is also related to the flow of fluids, it's more specific to the permeability of soil and filtration systems, not the velocity in pipes. The Christiansen formula and the Blasius equation are less commonly used for this specific purpose.