A capacitor is made of a flat plate of area A and a second plate having a stair-like structure as shown in figure. If the area of each stair is $$\frac{A}{3}$$ and the height is $$d$$, the capacitance of the arrangement is 

A

$$\frac{13\epsilon_0 A}{17d}$$

B

$$\frac{11\epsilon_0 A}{18d}$$

C

$$\frac{18\epsilon_0 A}{11d}$$

D

$$\frac{11\epsilon_0 A}{20d}$$