O is a point in the interior of $$\triangle$$ABC such that OA = 12 cm,OC = 9 cm,$$\angle$$AOB = $$\angle$$BOC = $$\angle$$COA and $$\angle$$ABC = 60°. What is the length (in cm) of OB?

A

$$6\sqrt{3}$$

B

$$4\sqrt{6}$$

C

$$4\sqrt{3}$$

D

$$6\sqrt{2}$$