A ball is dropped from a height of 5 m, if it rebound upto height of 1.8 m, then the ratio of velocities of the ball after and before rebound is :

Question

( A ) $\frac{4}{5}$
( B ) $\frac{1}{5}$
( C ) $\frac{2}{5}$
( D ) $\frac{3}{5}$