To have pressure wholly compressive under the base of a retaining wall if width
b, the resultant of the weight of the wall and the pressure exerted by the
retained, earth should have eccentricity not more than

A

$$\frac{b}{3}$$

B

$$\frac{b}{4}$$

C

$$\frac{b}{5}$$

D

$$\frac{b}{6}$$