$$\frac {PL^3}{3EI}$$ Is the deflection under the load P of a cantilever beam (length L, modulus of elasticity E, moment of inertia I). The strain energy due to bending is

A

$$\frac {P^2L^3}{3EI}$$

B

$$\frac {P^2L^3}{6EI}$$

C

$$\frac {P^2L^3}{4EI}$$

D

$$\frac {P^2L^3}{48EI}$$