Three trains A, B and C moving at speeds $$s_1, s_2$$ and $$s_3$$ respectively take times $$t_1, t_2$$ and $$t_3$$ respectively to cover a distance of x kms. If $$t_1 : t_2 : t_3 = 20 : 15 : 12$$, then $$s_1 : s_2 : s_3 = ...........$$

A

2 : 3 : 4

B

3 : 4 : 5

C

4 : 5 : 6

D

5 : 6 : 7