The area of the cross-section of a road fully in banking shown in the given figure, is

A. $$\frac{{{\text{s}}{{\text{b}}^2} + {{\text{r}}^2}{{\left( {2{\text{bd}} + {\text{sd}}} \right)}^2}}}{{{{\text{r}}^2} - {{\text{s}}^2}}}$$

B. $$\frac{{{\text{s}}{{\text{b}}^2} + {{\text{r}}^2}{{\left( {2{\text{bd}} + {\text{sd}}} \right)}^2}}}{{{{\text{r}}^2} - {{\text{s}}^5}}}$$

C. $$\frac{{{\text{s}}{{\text{b}}^2} + {{\text{r}}^2}{{\left( {2{\text{bd}} + {\text{sd}}} \right)}^2}}}{{{\text{r}} - {\text{s}}}}$$

D. None of these

Answer: Option A