A, B are end points of the longest chord of a circle of radius 3 units. If O is the centre of the circle and C is a point on the circle such that AC = AO,then the perimeter of the triangle ABC is

A

$$9 + 3\sqrt{3}$$

B

$$9\sqrt{3}$$

C

$$6 + 3\sqrt{3}$$

D

$$3 + 6\sqrt{3}$$