axial stress at corner point

Question

For the component loaded with a force F as shown in the figure, the axial stress at the corner point
P is

(a) $\frac{F(3L-b)}{4b^3}$                         (b) $\frac{F(3L+b)}{4b^3}$

(c) $\frac{F(3L-4b)}{4b^3}$                        (d) $\frac{F(3L-2b)}{4b^3}$