Loss of energy per unit volume due to friction in case of flow through a pipe at length L and diameter D is expressed as

A

$$4fL \frac{v^2}{2gD}$$

B

$$4f \left(\frac{L}{D}\right) \times \left(\frac{v^2}{g}\right)$$

C

$$4f \left(\frac{L}{D}\right) \left(\frac{\rho v^2}{2g}\right)$$

D

$$4f \left(\frac{L}{D}\right) \times \left(\frac{\rho v^2}{2}\right)$$