If q is the punching shear resistance per unit area a, is the side of a square footing for a column of side b, carrying a weight W including the weight of the footing, the depth (D) of the footing from punching shear consideration, is

A. $${\text{D}} = \frac{{{\text{W}}\left( {{\text{a}} - {\text{b}}} \right)}}{{4{{\text{a}}^2}{\text{bq}}}}$$

B. $${\text{D}} = \frac{{{\text{W}}\left( {{{\text{a}}^2} - {{\text{b}}^2}} \right)}}{{4{{\text{a}}^2}{\text{bq}}}}$$

C. $${\text{D}} = \frac{{{\text{W}}\left( {{{\text{a}}^2} - {{\text{b}}^2}} \right)}}{{8{{\text{a}}^2}{\text{bq}}}}$$

D. $${\text{D}} = \frac{{{\text{W}}\left( {{{\text{a}}^2} - {{\text{b}}^2}} \right)}}{{4{\text{abq}}}}$$

Answer: Option B