If flexural rigidity of a column whose length is L and the loaded end is free, is EI, the critical load will be

A

$$P_c = \frac{\pi EI}{(4L^2)}$$

B

$$P_c = \frac{\pi^2 EI}{(4L^2)}$$

C

$$P_c = \frac{\pi EI^2}{(4L^2)}$$

D

None of these