A short column of external diameter D and internal diameter d, is subjected to a load W, with an eccentricity e, causing zero stress at an extremefiber. Then the value of ‘e’ must be

A

$$\frac{D^2 + d^2}{8 \pi D}$$

B

$$\frac{D^2 + d^2}{8D}$$

C

$$\frac{D^2 - d^2}{8D}$$

D

$$\frac{D^3 - d^3}{8D^2}$$