The angle of elevation of a flying drone from a point on the ground is $$60^\circ$$. After flying for 5 seconds the angle of elevation drops to $$30^\circ$$. If the drone is flying horizontally at a constant height of $$1000\surd3$$ m, the distance travelled by the drone is:

A

2000 m

B

1000 m

C

3000 m

D

4000 m