Subject :NSO Class : Class 9

A boy moving with constant acceleration from A to B in the straight line AB has velocities v_{A} and v_{B} at A and B respectively. Time taken by the boy to move from A to C is twice of that from C to B, where C is the mid-point of AB. The ratio of v_{A} to v_{B} is

A1 : 2

B1 : 3

C1 : 5

D1 : 7

how???