Pressure drop due to pipe fittings can be estimated by the equation, $$\frac{{\Delta {\text{p}}}}{\rho } = 4{\text{f}}.\frac{{{{\text{L}}_{\text{e}}}}}{{\text{D}}}.\frac{{{{\text{V}}^2}}}{{2{\text{gc}}}},$$    where, L_e = equivalent length of straight pipeline which will incur the same frictional loss as the fitting and D = diameter of the fitting. The value of $$\frac{{{{\text{L}}_{\text{e}}}}}{{\text{D}}}$$ (dimensionless) for 45° elbow and 180° close return bends would be respectively around

A. 5 and 10

B. 45 and 75

C. 180 and 300

D. 300 and 500

Answer: Option B