The height of the pillar when it is found that on walking towards it 60 meters in a horizontal line through the base. the angle of elevation of its top changes from $$30^\circ$$ to $$60^\circ$$. its height (in meters) is

A

$$15\sqrt{3}$$

B

$$30\sqrt{3}$$

C

$$45\sqrt{3}$$

D

$$10\sqrt{3}$$