A short column of external diameter D and internal diameter d carries an external load W. The greatest eccentricity which the load can have without producing tension on the cross section of the column is

A

$$\frac {(D + d)}{8}$$

B

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

C

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

D

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