The height at which the acceleration due to gravity becomes $$\frac{g}{9}$$ (where g $$=$$ the acceleration due to gravity on the surface of the earth) in terms of $$R$$, the radius of the earth is

A

$$2R$$

B

$$\frac{R}{\sqrt{2}}$$

C

$$\frac{R}{2}$$

D

$$\sqrt{2}R$$