Two loads P act at right angles to one another at the free end of a cantilever beam having square cross-section $$d \times d$$ and length l on the vertical and horizontal faces. Maximum bending stress in the beam will be equal to

A

$$\frac{6 Pl}{d^3}$$

B

$$\frac{24 Pl}{d^3}$$

C

$$\frac{12 Pl}{d^3}$$

D

$$\frac{18 Pl}{d^3}$$